Well last night, I decided to join once again in the college fun. (A mate of mine gave me a beer and when we went for wine I forgot the "No Mixing" rule, so I was quite drunk) I was also joining the party in hope to bump into a girl I met 2 days ago over a game of pool. Easily a 9. I did, but only for a short time and I didn't close. (Maybe I'd get another chance tonight again in some of the clubs we're heading to later. I would definitely see her next week if not tomorrow I thought)
After the uni closed, I went along with some friends. On the way to a friend's house for more drinks, I notice a girl who I had met a few days ago also. She's a 6. Somewhat attractive. And she's showing interest. She is in the same class as me. At the friend's house, I'm kinda in the mood and quite damn drunk and I make a move, we make out. I told her I was looking to just have fun, no strings attached and she told me she wanted to be friends with benefits no strings attached also. I agree and ask again for to confirm there are no strings attached. She also mentioned that she doesn't "do it" with guys just on the first day, so we just make out and such.
I want to ask you guys for advice about "Friends With Benefits".

Do/Did you have some? Does it cause any troubles? And most importantly: If I do continue to have this friend with benefits who is in the same class as me and a lot of other girls that I like, will it affect my chances with them?