What is, overall, safer for your body: alcohol or marijuana?

1) I have a large amount of course work, which is combined with a job and extra-curriculars, and while I want to succeed in all of them, I find that I simply don't have enough time, even though I currently sleep only 4 or 5 hours a night. I mentioned this to a group of my friends here at school, and it turns out they all take stimulants to help them manage jam-packed undergraduate life. The pills are called ADDERALL and PROVIGIL. I have acquired some for myself, but before I take them, could you tell me if either has serious health risks? I do not have any other health problems or take any other medications. A few of my friends tell me that they sometimes stay awake for as long as 3 or 4 days. If it is reasonably safe, that would be great! Thank you.

2) Given the fact that this is a top-notch school, it's total hoo-ha that you haven't included any info on all the non-hard core, but still illegal, "study stimulants." Is all this ADDERALL gonna do me permanent damage or what?

My girlfriend tells me she uses marijuana to calm herself if she is having a stressful day. She has been doing this for many years. She says smoking pot is like self-medicating — it is better than using anti-depressants. She also claims smoking pot helps with depression because of how it helps produce serotonin in the body. What is serotonin and how does it help depression? Does smoking pot really help with managing your anxiety, depression, etc.?

I want to know what it is when you spontaneously trip without dropping tabs or anything. I've never had any drugs except marijuana. It is weird. I know that tripping is an induced psychosis, so am I psychotic or what? I was seeing a shrink and will be going back into treatment next semester. I think substance use is boring and a complete copout on life. I've made a lot of discoveries without needing to trip. Why does this happen? Tell me what you know.