No i think alot of arc on your ball is a good thing because its give a better chance for the ball to go in. If your ball doesn't have alot of arc on it then its means that your not putting alot of arc your shot.

not at all.It will be harder to block and give you a better chance to make shots. A flat shot will result in bricks

Alot of arc on a jumper is definantly a good thing it really helps your acuracy and gives you better a chance of swishing it. It also helps you get the ball over defenders.