Heres my suggestion. Forget what you know about time signatures first of all.
It still applies, but you have to think about it differently when playing rhythm guitar. Time signatures are a logical anaylsis of time, but with rhythm guitar the beats are based more so off of how the music feels. Once you understand this you will know what I mean when I say that you will mostly be playing along with the drummer. Forget the strumming patterns that you all ready know. The drummer will establish your strumming pattern for most songs.
Three situations can occur in the rhythm section of the band in regard to the bass player. The bass player can be playing exactly what the drums are playing, he can fill in some beats that the drums are not playing, and the drummer could fill in some beats that hes not playing. Sometimes you can play exactly what the bass player plays or what the drummer is playing. Sometimes its cool to play the notes or beats that they're not playing. Sometimes its cool for them to play the notes or beats that your not playing.
The best way to understand rhythm guitar is to understand the drums, and the bass guitar. I learn by doing things myself. Whenever the band has some free time It would probabily be a good idea to pick up the bass guitar and jam with the drummer, and also to sit down at the drum set and jam with the bass player.
Although you may not like these styles of music you would benefit from listening to some heavy metal music. They usually have the most complex strumming patterns that I have ever heard. Rap, and funk music usually have cooler beats on the other hand, but not as interesting. The music in Africa played only on drums has some really cool rhythms at times (my apologies that I don't know the name of this style of music.) Lest we not forget about blues rhythms.
But in all honesty, if you know how to play classical guitar, shouldn't you be the lead guitar player?
Bass guitar is the answer to everything