People developing ReactOS also usually join our
IRC-channel #reactos
on freenode.
If you become a steady ReactOS developer, somebody will offer you SVN
write access so you don't need to submit everything to bugzilla, but
that will take a while...
If you think you can participate in develompent of any particular
subsystem/part of Ros you should speak with Fireball on #reactos. He may
designate you to some specified field. This could speed up the joining
process, but do it only if you feel experienced enough.
Regards
Caemyr