It sounds like light switches and lights are usually wired with 14/2 cable. Is it okay to use 12/2 cable instead? Would I need special switches?
As long as you have a 15A circuit breaker on that circuit, it's OK to use 12/2 NM cable for your lights. Since the maximum current on the circuit will be 15A, you won't need special switches. You should label the wire that it is 15A, not 20A, so that someone else doesn't come along and treat it as a 20A circuit.
You'll probably also find that you won't be able to use the insertion fittings on the back of the switches (but that's OK, IMO, because I always use the screws), and you definitely won't be able to use the electrical nuts that come with your lights, so you'll have to get your own (and making a secure connection might be trickier with 12 gauge).