I think you've got it (close enough).
Right. During the collision, the net force on the ball is upwards.
"net" force means the (vector) sum of all the forces. On the ball we have two forces: its weight (acting down) plus the large force of the table on the ball (pushing up). The sum
of those two forces gives a net
It's the net
force that determines what happens to the body--how it will accelerate. You can have high forces applied to a body and still have a zero net
force. For example: step on a rubber ball, squashing it against the ground. There are several forces on the ball: your foot exerts a high force, the weight of the ball exerts a force, and the ground pushes up with a large force. But the net
force is zero: they all cancel out.
Right. When the table exerts a force on the ball, the ball exerts an equal force on the table. That's Newton's 3rd law. (Note: this applies to the individual forces between bodies, not the net