The PGA do not approve Golf balls, the USGA and R&A rules committees do. They both publish a list of conforming golf balls.
Yes
There isn't really a limit of the amount of golf balls you can have. But if you run out of balls, you can't turn in a score card, and you are disqualified.
tytlist
Yes... they are USGA approved balls.
A PGA Tour player, can use any golf ball that is on the list of conforming golf balls, which is published by the USGA and R and A. The PGA Tour operates a one ball rule, this means if the player tees off with a Pro V 1 x on the first hole, the only ball they can use during the tournament is a Pro V 1 x, or they will be disqualified.
Professional Golf Association
PGA CHAMPIONSHIP
PGA Tour Golf Team Challenge happened in 2006.
PGA Tour Golf Team Challenge was created in 2006.
Callaway Golf PGA Junior Series was created in 1996.
Yes they can.
A Titleist Driver can be purchased at many golf stores. Here are some of those stores 3 balls, Golf Galaxy, global Golf, PGA Tour Shop, Golf Locker, Amazon, Ebay, 2nd Swing, and Fairway Golf USA.