From my point of view, that's a very complex subject. One might ask, how does alcohol affect my body in comparison to someone else? Each energy system works a little differently. Almost as if we are (symbolically) each on our own 'frequency' like a television or radio. We are sending and receiving billions of bits of information every second. Since each system is so different, one would have to experiment and see for oneself.
I know that the heart, liver, stomach, kidney, bladder, and lungs, (you exhale the alcohol, the liquid that the alcohol was in is expunged thru the bladder) systems are affected and slowed when under the influence.
As for doing QiGong while you are drinking, say one drink, it really couldn't hurt. I guess you'd have to try it and find out. I don't recommended doing it when you are completely smashed, seeing as the mind has extreme trouble focusing in that state (and one of the main reasons to practice is to master and overcome the flaws in our attention and focus).
This one's kind of an unknown to me. I have experimented under the effects of other things a while back, which I shan't mention here. But I have concluded that some substances actually connect you with the earth and universe even more so,(such a shame those were outlawed, humans are stupid creatures some times-I should have a choice) and some will give you the -illusion- that you are one, when actuaully you are really distracted.
So yeah, it can't hurt to experiment as long as you are in a safe environment and setting, right? Try it and see...
If anyone else knows more about it, we'd like to hear your input.
~Z