Radiator

Does a higher flowing and lighter radiator give you gains or better acceleration????

The radiator is already pretty light. I don't think you can get a lighter one, if ya can it would be by much.
As for the other Question I'd say no, just keep the engine cooler

Those gimmicks of hp gains on an aftermarket radiator is just BS.
Do note, a new radiator WILL make ur car run a lil cooler cause of the old ones being shitty inside.

If ur really concerened about losing weight. loose ur ac if its not working or dont need it. Its not that hard to put back if u want it.