any one know of a resource to efficiently teach pianists rock rhythms and accompaniments?

I'm thinking of an etude (one can switch the keys) with every rockbeat configuration included.

When I learned guitar, I learned about 10 different ways to strum.. I'm supposed to create accompaniments for rocking church music and can't get beyond arpeggios.

I can't really do this type of thing by ear.

The Pop Piano book by Mark Harrison (Hal Leonard Publishing). It's a monster of a book (approx. 300+ pages). It will last you for years!!!