1. I barely get asked for taking pics probably because I'm too busy doing more productive things. If they ask me I really tell them something like:
Can't you see I'm busy? But look at that dude[points at greatest AFC in the room]. Ask him. He's been checking you out for a while but I think is too afraid to approach. Don't be mean. Give him at least something he can dream about.
Believe it or not...they barely ever go to the dude and just laugh

... that's something you can work on after that.
2. Well... just avoid them?
3. Answer #1: Oh...you're trying to get me drunk. Well better brace yourself then. I'm not that easy.
Answer #2: Okay but I'm not taking you home.
Answer #3: No way... I'll get super wasted and hump every hot chick...again
4. DON'T IGNORE THE FATTY. Never ever do that. She will stalk and cock-block you the whole night. Just have fun and befriend her and hope the best that she's not as crazy as fat.
5. I believe a guy called Mystery wrote several chapters about situations like that so I'm not gonna bother listing things you, I assume, already know.