As far as dry cleaning goes, you don't need to clean stuff that often. First thing I do is keep a good rotation (which last fall I was guilty of neglecting cause I was wearing the hell out of my flannel cargo trousers!). When I get home from work I hang the out of the closet on a door hook and brush them out with a clothes brush. Kent brushes on eBay are great and can be had for cheap. They're normally super expensive, but they put their seconds on eBay because there are knots in the wooden handle, nothing to alter how it works. I let them hang out for a day or two before putting them back in the closet. This usually means I don't need to clean them at all, but if I really wear a pair to death, I'll have them cleaned at the end of the season, but in garment bags and hung in storage until they're ready to come out again. As far as the right way to hang them in the closet, just make sure you fold over the crease, leave the trousers unbuttoned and unzipped, and most importantly that they have enough room to breathe in the closet. Same for jackets. Hope that helps.
As far as the Kent brushes go, is there a specific seller that has them in stock for cheap? I'm searching for "Kent brushes" on eBay right now, and there are a thousand different results popping up, and all of them look pretty expensive ($40-$80).