Weights on your wrsit will build endurance in the muscles they add resistance to when punching, not speed...

Personally I just think they make a weak link in the chain (you use your whole body to punch... ) and the quality of your training is lowered... its more beneficial just to wear gloves.

Plyomtetrics are good, just be careful when you do them. Have some one who knows what they are on about demonstrate them to you...

no matter how many words I type I can't subsistute actually showing you something