Cats are good pets for people who work, they sleep a lot in the day. I agree with zonetrooper that in this situation 2 cats would be better than one, though.

Yes if you get the cats a water fountain and automatic feeder, and have plenty of litter box space, they can be left a couple of days, and they prefer that to traveling. (Unlike a dog, who would rather go with you).

Talk to the shelter, they may know which individual cats in their care would be good for your situation.