Re: learning a second instrument
I'd say piano. It is an easy way to get some of the music theory and learn to read notes. At my drumschool I learn a bit piano too because my teacher says the music theory is something every musician espescially in a band should know it (even the drummer).
Besides that, I don't know what instruments are used in your band, if there isn't a pianist you could become one so you could play alot more songs.