having a legit sparring partner to practice timing and distance control. they play a good part of the punches perceived speed
Your punching technique is the the foundation for generating power, having a good trainer around to help you is key. Try and focus on getting that torque when you twist your hips, your legs are where most of your power is coming from and the snap at the end of your punches is coming from forearm and wrist, so to get more pop in your punch I use wrist roller and for bigger stronger legs I do countless amounts of squats, to where I could barely walk up steps, I only do that twice a week though. Just remember good technique, and envision yourself throwing the punch with proper form in you head, and then try and reinact it how the heavybag, it helps have a good trainer to reinforce good technique as well.
4 endurance do non stop explosive punches with weights say about 4 sets of your max but keep on doing it and your max will get further and further this helped me hopefully it'll do the same for you
from what ive heard doing that with too heavy of weights wrecks your arms after a while, i dont know about doing that one
ive never done it so i cant speak from experience but 2 or 4 pounds every now and then thrown into a workout maybe yea. i know of people that do stupid **** like punching with 20lb weights in there hands, thats not good for you. anyways, endurance wise if you can get someone else or some way to randomly have it called try doing sprints on a heavy bag. work the bag normally and at the other persons call or however you figure it out, throw straight punches as much as and as fast as you can until youre told to stop, then continue working the bag normally. the best way to build endurance i think is just to punch yourself out basically and build on it, it seems like thats what my coach does to us
You continiously ask the same questions albiet in a different manner. Your Google-Fu is weak and so is your spelling. That which you seek cannot be given, but earned through research and applying the hard work to reach your goal.