User/login questions

I wish to implement a web-based login system where the user logs in and gets
a list of available databases. This involves several things that I have
questions on:
1) Connecting to the DB and logging in (Must the user connect to a
database?)
2) Finding out what databases the user has access to (How?) without having
to maintain a copy myself. (Can it be pulled from some system table, or join
of system tables? (i.e. SELECT db_name FROM something WHERE user='me' AND
granted_perm='SELECT')

Also, I'm stuck in 7.2 land, with a planned upgrade to 7.4, when it comes
out.


Thanks!

Jason Hihn
Paytime Payroll