Hello :] You aren't planning on getting two males right? Because they are very territorial and almost always fight, even if they are being kept together at the pet store. Besides girls love company and are much less stinky than the boys. Mice do chew and I am sure they can chew on plastic, but they all don't so it would be hard to tell. I have always kept mine in a 10 gallon aquarium, which is big enough for two, but of course the bigger the better! As long as they have little wood chews and you spend enough time with them, they would be fine in a plastic cage. Are you wanting a bar cage? Because if so make sure that the bars are no more than 1/4 of an inch or they can slip out, but if you find one mice love them and love to climb. And they need a wheel because they will run ALOT!! Lol. Good Luck, and be careful...they are escape artists!