Variables or hooks? Help!

[Sophonax]

Okay, so I'm integrating the RealChat software to my forum.
Quite a bit of easy coding, but there's alot of tricky coding.

My vBulletin knowledge is limited, thus I come here to ask a few.. Erh. "newbish" questions.
I'm pretty sure most of you know this by heart, so I'm hoping for a quick answer.

As I said, I'm integrating my RealChat software, but I need a few variables to call out certain things. I've been spending several hours on this little problem.

I need the variables or hooks (Ugh, not really sure what you call these. =p) for these:

Age
Member Group (admin/mod/regged user/guest/waiting activation/any custom group)
Post count

Go ahead and laugh at me. 'Cause I do. xD But please help? <3

Also, if someone feel like helping me, I need help to create a small function that will access the database to see if the username has been registered. If yes -> print username is registered. If no -> load applet. I got something from a friend of mine who pretty much explained who to code this, but then again, I don't know this part of vB.

[ Edit: If this is in the wrong forum, sorry. ^^; ]