Hey DrSad,

You're asking a lot of questions here, so I'll just be blunt and enumerate....

1) If you sign with a publisher, it's exclusive, and they take 50%.

2) If you wish to place your music with a "library", then that may be exclusive, (i.e. the library is taking on the role of "publisher" ) or non exclusive. eg if they place the music, then it's a 50\50 split.

3) Always go for the non-exclusive deal. It's still 50/50, but doesn't tie your music up.

4) If the publisher is the real deal, then sign with a reversion clause. ( In other words, if nothing happens, say, after 2 yrs, you're cut and dried to find another publisher )

5) Be aware that there are "publishers" and there are "publishers". I'm a "publisher", but not in the true sense of the word. If you want a real publisher, check out Dude McClean, http://www.songconsultant.com/ No endorsement here, but just real in terms of songwriting.

Good luck....

cheers, niteshift