I have a rack built the SAME way. There is a youtube video that pretty much lays it out step by step. I use flex-watt. When I made the rack, I essentially made it upside down so that there was a goove pre-made to put my flexwatt on. I mounted it on a piece of panel board covered in foil tape and mounted that on a block of wood and just set it in my rack. If you want some pictures, I can get some for you.

As for what to breed, like everyone else has said, breed what YOU want to produce. I have 5 corns and 3 BPs right now. You can see in my signature what I have. I personally LOVE lesserbees and BELs, so next season when I pair, I'm hoping to get some lesser bees and hold back one or two to make some BELs. I have one more spot on my rack (mwahahahaha) that I'll fill with probably an albino or pied girl in the near future.