Cokin style (square) filters are excellent. A lot of us use them, and I love mine. They don't make the lens unweildy at all.
Ref the CPL, as it rotates it will be awkward, but not impossible to use them if it has the thread. You will need to watch the focal length, the wider you go, the more chance you have of the lens seeing the filters and holder as vignette in the images.
You can get a CPL to fit intot the coking if you want.
Also check out Kood filters and holders, they are cheap and good.
there is a link on filters in the link in my sig.