If I wear an XL hood and a L wetsuit, what size hooded vest should I get?
Also, what kind of effect will this have on buoyancy? AKA, how much weight will I need to compensate for it?
The large hooded vest will have a large size hood on it, so if you wear an XL and a large is too tight, then this will not be good for you. If you can get away with a large hood, then no problem.
You will most likely need about 3-4 lbs to compensate for this hooded vest.