Brett, to answer your third question. The carburetor on the DA50R, and 99% of gas engines, has a pump built in, DO NOT RUN MUFFLER PRESSURE TO THE TANK. We all try to mount the tank on CG on gas planes. To answer your fourth question. The DA uses significantly more fuel during the rich run in period. I got 10 minutes on 16oz, but when fully run in and leaned out, 16oz will easily last 15 minutes, unless you're racing. To be on the safe side, install a 20 oz tank, and keep flite times to 10 minutes in the beginning and check fuel levels after flights.
DKjens