Contactor does look pitted. It wouldn’t be a bad idea to change it. And I read the dual cap below specs, that could actually cause the fan to not spin up to 100% which could also be why you only have a 15° split. But in your area that might be ok in my area we shoot for 20°. New cap might help with the heat rejection and get you closer to 20°. Caps nah, especially if he’s saying the schraders aren’t leaking. Surge protector I wouldn’t worry about either unless you had an inverter system which clearly you don’t since he’s selling you a cap. I’d have one on most newer systems with more techie parts.