"I did it of my own free will."

This means I did it without being compelled - by someone, or by external circumstances, or by mental illness - to do it against my wishes. "I did it of my own volition" is synonymous: the act arose out of desires (volition) that were produced not by threats, coercion, or disease, but by the normal pursuit of my life and projects. So free will as used in a naturalistic sense (as it will be below), does not mean that the person acted independently of causes, since after all volition is itself a causal product of one’s environmental and biological situation.

"Clinton is morally blameworthy for having cheated on his wife."

Since Clinton presumably knew that having sex with another woman constitutes infidelity, and knew that infidelity is wrong, with a social price to be paid for its discovery, he counts as a moral agent, someone liable to be blamed (punished) for his transgression. Moral agents, naturalistically speaking, are just those persons that can anticipate and be influenced by rewards and sanctions, which is why it makes sense to apply them just to moral agents. Those incapable of such anticipation, such as the very young and the mentally incompetent, don’t count as moral agents since they can’t be expected to be influenced in this way. (They have to be influenced by more direct means, i.e. by constraints imposed by supervising adults.)

One need not have free will or be responsible, in the non-naturalistic, "ultimate" sense, to count as a moral agent, nor are this sort of free will and responsibility the necessary basis for morality. Moral rectitude results from the careful social shaping of an individual, not from choices made independently of causal factors.

1. Being responsible for one’s behavior: "I’m responsible for causing the accident." This means the accident was my fault: my bad driving resulted in a collision and I was mentally competent and I was not under anyone else’s control. Because I was sane, had the capacity to anticipate the consequences of driving badly, and drove badly, it makes sense to apply sanctions to me (paying for the accident directly or in higher insurance premiums) in order to reinforce the determination to drive better in the future. Being responsible for one’s behavior implies being justifiably liable for the consequences of one’s acts, whether good or bad; that is, one is responsible by virtue of being a moral agent (see above): having the capacity to anticipate and be influenced by rewards and sanctions. Being responsible doesn’t have to mean that one is (impossibly) the first cause of one’s character or motives, that one is "ultimately" responsible.  
2. Acting responsibly: "Normally, I’m a responsible guy." This just means that I tend to act in ways that fulfill obligations or agreements.

"The ambassador is normally held responsible for the safety of embassy employees."

This means the ambassador is liable to socially agreed upon sanctions in the event that the safety of employees is compromised. Synonymous with being held accountable. Being held responsible or accountable is a means to shape behavior and keep it within agreed-upon norms. Knowing that he will be held responsible, the ambassador will be concerned about embassy security.

1. Retrospectively: "The boys refused to take responsibility for their actions" (the school shootings in Jonesboro, Arkansas.) Translation: the boys refused to acknowledge that they shot their classmates out of their own free will, that is, without being coerced or compelled by anyone. For them to take responsibility for the shootings, naturalistically, would be for them to explain their motives, how they planned and carried out the act, how they anticipated the consequences, and how they now understand the appropriateness of the sanctions applied against them. (To the extent they are incapable of this, they literally can’t take responsibility and aren't moral agents.) To take responsibility for one’s behavior, retrospectively, is to admit that one was in the full possession of one’s faculties, or at least mentally competent, and to acknowledge that the social consequences of one’s behavior (either rewards or punishment) are justifiable.  
2. Prospectively: "I’ll take responsibility for completing the proposal." This simply means that I agree to finish the proposal, and that if I don’t, I understand that I’m liable for the consequences. I also understand that if I complete it, then its fair to expect, perhaps, some acknowledgement that I fulfilled my end of the deal.

"The defendant was in control of his actions at all times."

The accused thief’s defense is that he stole in the grip of an epileptic seizure, but the prosecution claims that before, during, and after the robbery he was fully cognizant of what he was doing. The naturalistic reading of the prosecution’s claim is that the thief - that is, his normal motives, rationality, and skills - was controlling his behavior, not a delusional state borne of mental illness.

Note that this expression is often used with the non-naturalistic implication that an agent separate from circumstances (i.e. with some sort of blameworthy, contra-causal free will) is in control, and that this agent could have done otherwise were the situation replayed with all factors reset to be the same. But being in control of one’s behavior is simply to act deliberately, intentionally, and rationally.

"After drinking moderately for several months, he eventually lost control of his drinking."

This means he started drinking more than he initially intended or wanted to, despite whatever negative consequences ensued. The desire to drink immoderately overcame the good intention to stay sober. It doesn’t mean that some controlling autonomous will, independent of these desires and intentions, failed to operate, but that the net vector sum of motives and desires, as determined by various conditions, resulted in heavy drinking. Losing control simply means doing what one explicitly intended not to do, or doing what one would normally consider inappropriate.

"Given the circumstances, I think the captain exhibited remarkable self-control."

The captain very much wanted to reply in kind to the major’s insult, but his strongly inculcated discipline in the face of such provocations won out. Successful self-control isn’t the control of desires or impulses by an unconditioned self operating from a disconnected vantage point, but simply the process of one motive (ordinarily socially approved or derived) outweighing another (usually more self-serving) in the control of behavior.

Note that one could substitute willpower for self-control in the example above and not change the meaning. This means willpower is simply the strength of a particular desire, usually the desire not to give in to some other desire. It doesn’t refer to some general capacity to quell or control impulses from some unmotivated standpoint. Willpower refers to one side of the conflict of motive, usually the socially approved side.

"It was his personal choice, nothing else, to get involved in gangs."

This means that no one forced Manny to join the Bloods; he did it out of his own free will (in the naturalistic sense, see above under free will). Of course this voluntary decision, like the rest of Manny’s behavior, was the result of various antecedent conditions, so the fact that the choice was voluntary shouldn’t be construed as implying that it could have turned out otherwise, given these conditions. People make choices constantly, but they aren’t the result of some contra-causal free will operating in some crucial sense independently of circumstances.

"Clinton deserves more than just a censure for his deliberate lies to Congress and the country." 

To deserve a particular punishment, naturalistically, is to be liable for sanctions proportionate to the harmfulness of the behavior we wish to discourage.  Regarding this example, some think that mere censuring is insufficient to deter such gross misbehavior on Clinton's or his successors' part, or more abstractly, to safeguard the dignity of the presidency.   Therefore, Clinton deserves something harsher.  To deserve something is often thought to be necessarily dependent on having contra-causal free will, but we can usefully and legitimately talk about deserving blame or praise in a naturalistic context in which the function of moral language is to shape behavior.  The shift to a naturalistic understanding of "deserve" might, however, lessen punitive attitudes toward offenders.

"Clinton's behavior over the last 7 months is inexcusable." 

This means that even in the light of a complete understanding of why he behaved as he did, we are justified in demanding sanctions against Clinton, since these are necessary to safeguard the dignity of the presidency.   If we came to feel, via expressions of abject contrition, that Clinton was sufficiently chastened so that

1. he wouldn't repeat his misbehavior, and
2. that his humiliation serves as an adequate deterrent to his successors

then perhaps we would excuse, or forgive, him. 

Naturalistically, to excuse or forgive a morally responsible agent is to have the desire (and need) for sanctions diminish in the light of assurances that they are no longer required.  If an offender doesn't count as a moral agent - e.g. a young child, someone in the grip of psychosis - then he is automatically excused from sanctions that would otherwise apply (although he may be subject to restraint, therapy, etc.).