Personally, I haven't seen ! before nicks before, however, the % means "halfop" (which is what the +h channel mode is for). Halfop users can voice other users, and, on SOME networks, kick other users and certain other commands. Ask in the network's #Help channel.
If the #Help channel can't help you, you might want to check out the network's website - if you don't know the address, search on
Google. If you know the IRCd that the network uses, check out the IRCds home page too. You might be able to find it out by typing
/motd but you can also see it when you connect to the network, something like this:
Welcome to the Some IRC Network Yournick!user@host
This server was created Sun Apr 4 2004 at 20:15:49 EDT
arnie.uk.eu.some.net CoolIRCd-6.14 LoTs oF LeTteRs HerEThe bit in red being the name of the IRCd (CoolIRCd) - Again, use Google to find out the IRCds web address, documentation may be there.
I'm sure someone else will know though!
Regards,