Kevin,

Cap's generally need up thrust due to the high thrust line and low center of drag. That's why when you come off on the power on landing they balloon. You'll have to fine tune it but 2deg up is usually the rule.
Troy built models sells the gear, they're nice.
Putting the tank on the cg is an excellent way to go. I opened up my formers and slid the tank back to the servo's. Use a Perry pump or a Cline regulator and you'll be golden. Don't try to do it on venturi suction alone.
This is a great combo, let us know when you get it flying and what you think.
Chris