This is very subjective.
Clomid is indeed used in male infertility issues.
I don't think your doctor plans to keep the dosage 50mg for longer than couple weeks without rest period. You need to know there can be side effects including blurness of vision and can lead to permanent damage to vision, if you experience this you need to stop immediately and contact doctor. It's rare but it can and have happened. Other side effects are mood swings, much like our beloved wifes so nothing we wouldn't had seen or experience.
Clomid increases sperm count and mobility.
The fertility success rate is impossible to say it depends on your partner too, but studies show everything from 14% to 36% ( highest being with antioxidant treatment with vitamin-e ).
It's not magic drug that will guarantee you child, none of the studies i've seen suggests even 50% chance, so be prepared to try for the baby for quite a bit if you don't get lucky. Chances are also that it doesn't boost your fertility as that is reported also in some cases.
Wish you and your family best of luck in your baby endeavours and life.