For which senses of simplified 制 would I use the traditional form 製?
Historically they were the same character. Later the meanings split, 製 is usually the verb meaning to make, and 制 the noun meaning the system, or more abstract things. 

Uniform should be 制服, because it means the clothing following certain rules/system. 製服 could be literally interpreted as clothing-making. Regarding the meaning of overpower, it must be 制服.