I haven't had any problems with my landing gear either. I did reinforce the landing gear block inside the fuselage a little. I added tri-stock and lots of epoxy.

I used the stock engine mount and haven't had problems, but if you don't want to use the Dave Brown mount that CeeGee mentioned, I'm sure you can find something that lines up with the existing holes in the firewall.

I used a Sullivan seamless fuel tank in my Ultra Stick....but it was pretty much personal preference, although I've heard about the stock tank splitting also. I've been putting the Sullivans in most of my planes for the last couple of years.