I'm building a set for my Laser 3D our of aluminum.
2. Yes, a bit tailheavy, Or a lot. You want the rear end to sag on landing so they don't dig in.
3. Unless you want to continue going straight until the plane stops, I'd put a ridge on it .
4. I'm using the TLAR method. That Looks About Right.

They're not much different then wheels. The only difference I can think of is they take more room to stop after touchdown.