The impulse (the variation of momentum of the ball) is related to the force applied by

where

is the variation of momentum, F is the intensity of the force and

is the time of application of the force.
Using F=1000 N and

, we can find the variation of momentum:

This

can be rewritten as

where

and

are the final and initial momentum. But the ball is initially at rest, so the initial momentum is zero, and

from which we find the final velocity of the ball:
The second one, air is a poor conductor. If it weren't it wouldn't be used as such in construction. It's not the best insulator, but is quite efficient, and much cheaper to include a layer of air inside a wall than to add additional layers of asbestos :)
The word "gravity" belongs between "of" and "on".
Answer:
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