I rarely use any cloth at all, just mat. If I were building a boat I would alternate layers of mat and cloth, but for what we are doing just mat alone is fine. Mat also comforms to the curves and bends easier than mat and tends to bite in better.
As for pulling the excess resin off, there is a fine line between having the mat "resin rich" and "resin starved". If it is too much either way it can affect the strength and ability to properly saturate the mat. But fiberglassing is such a forgiving medium that as long as you wet out the fiberglass so it is translucent you will be fine.
I don't use a roller much, but I just buy a lot of throwaway paint brushes and dab resin onto the mat, pushing it down and soaking it. If you want to soak up some of the excess resin you can lay down the last layer of mat dry and watch how much it absorbs, then add just a little to make it wet.
One thing I can not stress enough is to use fresh hardener. Polyester resin ages fairly fast and sometimes even the stuff on store shelves is stale. I buy mine at a marine store that turns it over fast.
Don
