Is anyone work with GameHouse, Big Fish Games, iWin, Reflexive, Steam etc. game portals for 3rd licence game distribute? Which portals is very reliable? Do they demand the source code of the game? How do these companies work? How can I get my rights guaranteed? And, do these companies for payments problems? Thanks!

#3. No, they don't need your source code.
#5. Consult your attorney and get your game copyrighted. And when you get a contract from the site company, have your attorney read it before you sign.

Others will reply to your other questions.

Thank you for reply.