[syntheticdarkness]

first question, all jobs have different pay, among other things.
http://www.bottledbrainsdirect.com/careers.htm

second question, yes school is always good.
http://www.bottledbrainsdirect.com/school.htm

third question, depends on the gang you join, and usually gangs want lvl 5 or higher at the minimum, keep working and you'll get there.

Check out this page as well.
http://www.bottledbrainsdirect.com/begin.htm