I want to know whether masturbation can cause "Erectile Dysfunction" and/or "Premature Ejaculation". What are the benefits of masturbation and how many times a week is recommended (is good) for a normal male?

Masturbation is normal and won't harm your health. If you masturbate a lot, your sperm count can be reduced because your body only can make so much, but they quality will be higher usually. It won't cause erectile dysfunction and The more you masturbate, you'll probably become less sensitive, so I don't think it can cause premature ejaculation at all. It's healthy and normal to masturbate if you wish, there's no set guidelines though haha. You may want to check out this website for more information.

Masturbation: It's Normal, Healthy and Okay to Masturbate!

Actually it's the contrary. Masturbation is usually recommended as means to control premature ejaculation. I am not sure but I think it also helps in preventing prostate cancer...