If I may just add a little here on the being able to read music subject:
Drum parts/charts by themselves are nothing more than guides. All they really show are specific "figures" that the arranger would like supported, most always, but not limited to, backing the horn section.. if .. it happens to be that type of band. I have backed singers within a quartet.. ( no horns ) .. that have a musical director and a BOOK of drum/charts as they are also looking for SPECIFIC figures they want played at certain times within the arrangement. The point of all this is:
Reading music/drum chart is just another tool to have in your arsenal. It really has no basis on whether you are or are not a good player. It has nothing to do with one's sense of time/groove/feel. Those three things are absolutes specific to each individual and would most probably be in place already. Being able to read just BROADENS the scope of what you can do and how much you can play/work in the music and entertainment business. It goes without saying.. ( but I'll say it anyway! ) .. that there are so many incredible drummers working out there as independents or within a succesful band that CAN'T read a single note, and you know what? Who cares!! They don't need to! Is a drummer that reads better than you because he can read? ABSOLUTELY NOT! It's just another very useful tool if, as John/PS so perfectly stated: You want to work professionally. Back different artists.. play shows.. fill in on gigs and sound like you've been there all along.. etc. I am very fortunate/blessed to work as much as I do.. and being able to read most certainly helped that along. Course...
... once you're on the gig, you have to deliver on the actual playing part too! As was so well put by BigE/John/55 WFL/Glenn et al... you DON'T have to read music to be an excellent player, but the ability TO read music really opens up what you can do as a drummer that likes to play/work, and get paid too!.. IF .. that's what you aspire to do. For most guys, playing within a band that does clubs, or jam nights, or even just playing/practicing by yourself at home, is GREAT! It's all what YOU make of it and/or want. Lastly.. ( and I apologize for the length on this novella! ) ..
I taught privately for 15 years and always insisted that my students at least learn the BASICS of reading music, and what I mean of course in this case as we are drummers: Rhythm. The main reason for that.. ( and my method was painless, so they all told me ) .. they could go home after the lesson.. open their notebook.. and actually READ what we had gone over that day, and practice it. Did they have to be able to read to be excellent/working drummers? No. But if they could, you'll get the gigs that so many others who can't read won't.
Tommyp