I'm not really sure what you're trying to say with the first sentence, it seems like 1 and 2 are not saying the same thing at all. I would phrase the sentence differently:
I drink too much to hang out with my friends as much as they'd like
This is saying you have a drinking problem that's affecting your social life. The (me to) isn't necessary here, but could be added. You can't say "there is a time" or "sometimes" or reference any particular time, since you're talking about a habitual, ongoing condition of your friends wanting to hang out with you. If you want to use choice 1 (which means something entirely different), you could say:
Sometimes I drink too much to hang out with my friends until they have
drunk enough to call it a night.
This sentence says you sometimes get too drunk too quickly when you go out with your friends and can't finish the evening with them - it's happened a few times, but not all the time. You use sometimes here because you are talking about particular (though unspecified) occasions. You also leave out the "they think" because it's implied that they are the ones deciding when they've had enough. If it were different, you could say for example "until the bartender thinks they have drunk enough", because someone else is making that decision.
For the second sentence, choice a) is definitely better. Here, you ARE talking about a specific person that's too drunk, which is you.