Qoole might be easy to use, but for sheer power (and precision) use QERadiant
http://www.qeradiant.com. If you decide to use that editor, you can find fine tutorials on
http://ricebug.qeradiant.com and also be sure to read
http://www.gamedesign.net's q2 tutorials.
As for texture editors needed for map making.... notepad.exe?

you shouldn't really be doing anything fancy with a text editor anyway, as long as it has a find/replace function it's all good
Prefabs can still be found (I think) on
http://prefabs.gamedesign.net somewhat old, and I'm sure that there are better resources out there... but it's one at least
If you can/want to make your own q2 textures you can find textures and just plain photos in this link archive (scroll down to the textures section)
http://www.planetquake.com/polycount/co ... inks.shtml
Phew

lots of copy paste from my bookmarks

hope that helps
-NRG