Breathe out through ur mouth as you push up. Breathe in when you go down
Bench press, flies, shoulder press, power cleans, military press - any upper body exercises will help you build the strength you need
Get a deck of cards lay it face down , pick a card whatever number you pick thats how many reps you have. Do that until you go through the whole deck only 10-15 second breaks
Do shoulder work, and arm work.. make sure you keep proper form when doing push ups for best results..after you burn out, do wall or knee push ups..