you can't run out of sperm..
masturbate all you want it's not hurting anyone
or anythingg
In this respect, the male body has a wonderful way of recovering and rejuvenating itself. Masturbating is a healthy act that will not impede your ability to reproduce; and it will not cause you to deplete or "run out" of sperm productivity.
Don´t worry, masturbation is natural and harmless.
To your questions:
1. No, you will not run out of sperm. Sperms are being produced by male bodies continuously, whether you release them by masturbation/sex or not. Analogy: if you pee every day, you will not run out of urine:). The amount of ejaculate/sperms can differ, if you masturbate more frequently, the amount can be larger after some period of time without masturbation and there can be smaller amount of ejaculate/sperms if you masturbate for the second/third time a day, but you will never run out of sperm. They are being produced in your body all the time and sooner or later there will be plenty of it ready to get released again...
2. Jerking off is not bad.
3. Masturbation will not affect your ability to have kids. It is not a method of contraception and it will not make you sterile.
The main question if you masturbate enough to ave this as a worry is whether you would have enough of a social life to meet a mate to breed with. No you won't run out of sperm, just societal interaction skills.