The likelihood of masturbating causing any of them is very small, masturbation alone is very very unlikely to cause impotence but using a stimulant like pornography to gain an erection gives a lot greater chance of that happening, masturbation is also good to help overcome premature ejaculation because you learn how to hold back on the feelings you get when you're about to ejaculate as you are finding when edging.
In reply to your other question about not being circumsised my answer is no you don't need to as the more your foreskin stretches the easier it will retract and go back over the glands when you're erect.
Best to save your masturbation for at night when the family is asleep or early in the morning. That way you can take your time and enjoy your masturbation sessions. It is good to hear you are using are edging technique to prolong your pleasure ... Make sure you ejaculate your semen in a tissue so you can flush in the toilet.. You won't have to worry about stains on your sheets or the scent of semen.
dont. just stop.