That track looks great, the crossover would be fun!
At the moment those plans have the width about the same as the average track width and the same length of ramps which give you 20 degrees but I was thinking of shortening the ramps to give 25-30 degrees. There will be other jumps, im hoping to use the tabletop as part of a double sometimes too. Most of the people at the club are relatively inexperienced at jumping so I think a more gentle approach at the start would be nessecary, I can always cut the ramps down in length later to give a steeper launch angle
Our hall is all polished wood and we dont own any carpet although I think trying to get some carpet for at least some of the jumps would be a good idea.