Semi-beginner with some questions...
Lipos are great, but not too needed on the 500 sq inch Slowstick. You can strap a car battery under it and fly.... well, almost. It can fly happily at 20 Oz weight, might even do ok at 26-28 oz. Ideal weight outdoors is 12-16 oz. Less is great, but you cant deal with too much wind.
Number one suggestion:
Shove a lightly sanded 3/8 sq balsa stick down the aluminum tube for strength. Not much weight, a ton stronger. The stick is prone to bend the fust at the wing leading edge.
Use clear packing tape doublers on the stabilizer and fin for strength.
Have some light foam replacement wheels ready on the first day to replace the broken originals. Unless you use a very light battery, the wheels are too light duty, actually just too brittle. Polystyrene.
The plane is a blast!