Re: learning a second instrument
i found guitar much easier to learn than piano, not that that should put you off but i just went for he easy option.
another to consider is that learning the guitar will also get you to a level were you can play most popular songs on the bass. as obviously they're similar instruments. im not saying youll instantly be amazing at both but im guessing your focused on drums anyway.
whatever you choose you'll deffinatley begin to appreciate your band members playing more and maybe that will help your drumming.
find a rainy weekend and go for it.