The shuttle to and from the airport is pretty reliable, but I think their last departure from the airport is around 11pm or so. I know I've missed it on a late flight. Call to check. Cab fare is around $10 with tip.
It's quite possible to hop around Reno on the casino shuttles, using the airport as a hub of sorts. The casinos are happy to oblige as long as you give the impression you'll be dropping some money at their properties.