The usage of "do" and what it implies in these sentences

Let's look at your first example (the one about drugs). The second example is, for our purposes, the same.

Do you do drugs?

This question is technically a polar (yes-no) question that essentially means:

Do you do drugs now?

The word "now" means that someone should answer based on their current habits.

Therefore, the answer "yes" would mean:

Yes, I do drugs now.

Conversely, "no" would mean:

No, I do not do drugs now.

This means that someone who has done drugs in the past but doesn't do them currently could answer "no."

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However, in reality, this question would usually (depending on the context) be answered as if it were non-polar (not yes-no).

For example, if your doctor were to ask you "Do you do drugs?", you would likely tell them about your full history of drug use (or lack thereof); this information is relevant, so the response would include it.

This means that someone who had done drugs in the past but doesn't do them currently would explain this situation to the person asking the question; they would not simply respond with "no."

However, if the history of drug use (or lack thereof) is not pertinent, the responder could answer with either a polar answer or a non-polar one.

For example, if a friend asks if you do drugs—and you used to but stopped—you could say either "no" or "I used to, but I quit."

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In summary, the polarity of the response depends on how relevant the information is and whether the responder decides to provide superfluous information.

The question Do you [dynamic verb] ...? is asking about current behaviour. Do you do drugs? means Do you currently do drugs? And Do you eat at restaurants? means Do you currently eat at restaurants?

So, answering with Yes! simply means that you currently do drugs. Whether the current behaviour started long ago or just recently cannot be inferred.

Answering No! means you do not currently do drugs. Similarly, whether or not you did drugs in the past cannot be inferred.

Finally, there is no implication in either the Yes answer or the No answer about intended future drug use.