About a week ago i started keepin a dream journal, doing rc's and also meditating.

This is some background info, skip it if you want:

I was remembering at most 1 dream a night, and other nights i would just have vibes on what my dream might have been about, but when i lie there for longer trying to reconstruct them, many times i will just wait too long and forget them even more.

I had been smoking weed like 3-5 times a day, and I stopped doing that completely, hoping that it might help, if only a little. (My tolerance was pretty good, so i dont think it affected it that much, but i had a few other reasons to quit anyways)

I live in a college dorm with a roomate, we are both night people, and it is very hard for me to have a sleep schedule. We go to sleep usually between 1 and 5 am, it is very random since everyone has different classes each day, and my roomie still burns a lot and often has people over late at night.

Questions:
I am willing to make a serious effort to have a sleep schedule, but i am not sure when my 'bed time' should be. I also want to start waking up during my REM. For that, would it be best to wake up every 90 minutes, or after 4.5 hrs, 6 hrs, and 7.5 hrs only? Any advice on how to fall asleep fast enough to time it? Is it OK to not follow a bed time on weekends, or will that screw up the schedule?

Secondly, I was listening to one of the subliminal messages on lucid dreaming they had on this site. It happened to be right after a meditation mp3 on my itunes, and so it came on right after i had meditated for half an hour. When it came on, I heard the subliminal message as clear as day. That is kind of unrelated, but confusing either way.

Thanks for any help, it is VERY appreciated.