The Dubro fuel tank is better than the Sullivan. It sits higher in the fuselage. That helped me a lot. You can use a larger tank if you use a 2 stroke. I get 10+ minutes with the Saito and an 8 oz tank.

The Kavalier is pretty light if you use Dubro foam wheels and don't add anything. I may take out my Futaba 3003 throttle servo and use a Hitech 55 that is only .28 oz. I recently bought one for another kit and it is very light. The 3003 is heavy when compared to the Hitech.

Don't worry about things, I felt the same way too. I learned some of this stuff too late.