Andrew and the kids,
here's my offering. New pieces needed in yellow. You can fill the larger gaps by making custom straights from the 10's and 4.5's that were removed. You'll still need a few small pieces. See the appendix in the FasTrack Module Specs. The 1/4 turn is included with the switch. You could park a second train in the front by isolating and switching power with a SPST toggle switch