check out this thread...
http://www.e90post.com/forums/showth...t=87271...then post up lots of questions. This is a common topic, but I'm sure you'll have some specific questions.
...like filters...
Filters can be used on just about any lens that I've used - just like a film SLR. I assume you'll stick with Nikon or Canon here. I've never gotten into Canon, but I have a rather extensive experience with Nikon. Both are excellent, hold them and see which one is more comfortable to you. What filters do you have in mind?