Shows in July

I have a couple quick questions:

I am visiting the city in July and am planning on seeing the following shows: West Side Story, Hair and Billy Elliot

a) Will all those shows still be playing in July?
b) Which will have discount codes available before July?
c) Which should I go ahead and purchase in advance for full price?
d) Any seeting recommendations for any of the shows?
e) If I have time for one more show, I am either going to see Mary Poppins or 9 to 5. Which one would be better to see?

thanks.

Pay full price for Billy Elliot. The rest, use discounts for, or do lotteries.

thanks for the help.