A-18:
Yes reading music is very important to understanding rhythm and music! You don't have to be the best sight reader, but if you don't read, you will have no format for understanding how to count, subdivide, and create variations with rhythm. Very few great drummers don't know how to read-they may be gifted natural musicians who have highly developed ears, but believe me, they are rare!
I can sight read most drum music-but if it's very difficult and I can't sight read it, I can understand it, analyze it and work it out so I can play it. Sight reading is crucial to being a legitimate studio drummer, and can be an asset in auditioning for or learning music for a lot of high profile bands.
I think that Ted Reed's "Syncopation" book is an excellent and simple method for learning how to read rhythms. Also a beginning snaredrum book is necessary for learning how to read rolls, flams, drags and other rudiments-there are too many to mention, so check with your local drum shop. Finally Louis Bellison's "Odd Time Reading Text" will pretty much give you all you need for reading and understanding odd time signatures, like 3-5-7&9.
Please get with the best local teacher you can find, to help you to learn these things- a small effort now could make a big difference in your success later!!!