So far as I know, Male rats once they reach adolecence have a real issue with other males. However, the breeder I got Rogue from said that as long as the ratties were rasied together, they get along just fine. She had two really huge males living together and they just played with each other lol, no hurting each other at all. As far as the food thing, just keep an eye on them and see if one is picking on the other. My two girls tend to keep things even although they can get obnoxious at times. The best thing like I said is just to keep an eye on them and make sure one isn't being shorted. To answer your question, yes you can spay and nuter rats. The surgery is expensive though and not a lot of people do it. I hear though that nutering males adds to thier lifespan but I don't know for sure if this is true. If you get your rats from the same place *same breeder or store* you don't need to quarrentne them from each other as they have obviously been in contact before. If you get them from two seperate places its wise to keep them apart for a while. I don't know for sure how long though. My reccomendation is get a pair of littermates if you can. I've noticed littermates tend not to get into fights nearly as often, in both male and female rats.

Hope that helped! Im not a total expert, but Ive had a few ratties . If anyone would like to correct me, please do so I can learn more!