First of all, good on your Chicken_65 for being such a caring person and asking for help on behalf of your friend- he sure is lucky to have you

I agree with what people above have said and there are a few things I'd like to add in the hope that it will help you help your friend.
Speaking as med student myself, I can say that what your friend is feeling and going through is common amongst med students, especially in the first few year. I know that that doesn't really make it any easier, but maybe your friend will feel a -little- better knowing that he is not alone. Please tell him not to worry that his friends will get sick of him- true friends are a very important source of support. "He's frustrated that he can't be disciplined, strong and mature like anyone else."-- as I said before, there are many people who are happy and content on the outside, but are inside nursing similar worries and fears and problems...do remind him of that.
With regards to your friend's concerns about study techniques-- first year is a year of discovery for almost everyone and it can be challenging to find a technique that works. Obviously I'm only speaking from my own personal experience, but I'm pretty sure learning every chapter word for word is unnecessary and possibly not the most efficient way of learning. However, if he can make it work, then that's great. But it does sound like other methods would be better. If your friend does feel he is struggling academically, there are people he can turn to for support in the faculty (I don't know which uni he's at, but I guess unis would have similar structures)- and he should definitely not be scared to ask for help if needed.
Another thing regarding study and grades is that it's not unusual for students to see a drop in their grades compared to school...uni is a whole different game, and scores which might have been deemed 'average' in high school may in fact be excellent in uni.
I'm no professional, but it does seem from some of the things your friend has expressed (hating himself, frequent mood swings, feeling distraught and frustrated at himself) that he may benefit from seeking professional help. Mental health problems like depression and anxiety are unfortunately very prevalent amongst med students in particular (this is something I'm pretty passionate about so sorry in advance if I start rantig haha), and it's really important that anyone suffering has appropriate support, and if needed, therapy and treatment. Friends are invaluable, but sometimes it does help to talk to a 'grown up'. Ask your friend if he's considered speaking to a counsellor at uni, or maybe his GP and encourage him to do so. I know from personal experience that admitting to a perfect stranger that things are going crap inside your mind is frightening, but once you do, your life can be changed!
You're right when you say nobody deserves to be in a situation like this, and I do hope that things start to look brighter for your friend...with people like you in his life, it's likely that they will