is there a restriction on painting?

Not really unless its some very obscure type of paint. In which case you’ll want to make sure to include it in your Bill of Materials.

Does anyone know roughly how much weight powdercoating would take up?

make sure you allocate the weight for it also. You might laugh, but sometimes it comes down to ounces.

As I recall, the Pink Team has to allocate 5 pounds to achieve their signature look.