The 9815 is agood HU to start with.

If you can fit a 6.5" driver up front I would try to use one of the 6.5" comps. If you have the space you can always try a 3-way setup but they are more difficult to tune and if you don't have experience you may want to stick with a 2-way setup.
If the K2p set is a 6.5" set then it would be high on my list as I really like it with a good deal of power on them. I also really liked the old Proseries comp sets but the oldest one I heard was the 6.4 set so if your 6.1 set is close to the 6.4 set in performance it would be right in there with the K2p for duty.

Amp wise I would try to use the one's with the most power and in the case of your sub setup the one that matches the ohm load.

For subs they are all pretty good choices. Any of those choices will likely get loud enough so pick the one you like best. Personally I'd likely any except for the Poly's (I'm guessing the Boston's are either 10.4's or 10.5's and if the DLS is a UR10 or Iridium).

As for a rear fill you can always put somehting back there and fade it out or remove it altogether if you don't like it. It' snot you're going out and buying more gear so it's there to play with and experiment with. Some people don't like rear fill and others do.