Answering the best I can since you didn't use any punctuations
1. You could, but if the pair is very aggressive could be hard on the female.
2. I would look at
www.tangledupincichlids.com and see what floats your boat. Jeff has tons to choose from as far as Amphilophus family is concerned. He aslo has a subforum here where he has pinned topics of photo collections of both Midas and Red Devils. Here is the link
http://www.monsterfishkeepers.com/forums/forumdisplay.php?f=86
3. No, just feed them a good diet and keep up waterchanges as well as have a good filtration system and their color and growth will be fine.
4. As for sex, no. You will need to get several growouts or get a larger one that Rapps(TUIC^) can sex. Trimacs are the only real Amphilophus that you can sex early because the female gets the blotch on her dorsal fin. With any others it's all about the venting.