Watch your teeth. Use your tongue. If your mouth gets tired, use your hand. Try sucking his balls gently to see if he likes it. Deep throating takes a lot of practice to control your gag reflex. When he's close to orgasm, try to keep the head close to the back of your mouth so that it's easier to swallow.
No. Get over yourself. Master shaves himself, so I don't have to deal with musk or a hair stuck to my tongue.
No.
Yes. You can stop thinking about your discomfort and start thinking about your partner's pleasure. The taste of semen isn't that bad.