On a stereotypical soccer ball there are 32 panels.
It is not advisable to paint a soccer ball. If it is a quality leather ball, any kind of paint would degrade the surface.
It's not correct to talk about "density" of a soccer ball. It's better you say "average density" of a soccer ball. It's clear that any soccer ball consists of different materials such as leather/plastic, rubber, and air. It order to find the average density you have to find the mass of a soccer ball and divide it by it's volume (in the first approximation you neglect the thickness of the shell (leather and rubber coats)).
Yes, both have a leather cover.
There is no official number of panels for a football (or soccer). There can be 20 (the familiar black and white one) or 8 or 12 or 14 or pretty much any number. These days the better quality balls tend to have less panels for increased aerodynamics. The panels themselves can be hexagonal, pentagonal, or almost any convex or (as popular today) concave shape.
On a soccer ball there are 12 pentagons and any practical number of hexagons that can make the soccer ball look spherical.
The leather ball bounces because it is full with air in it. If you remove the air then the leather ball does not bounce at all. While the aluminum ball (which I can only imagine, since I have not seen any aluminun ball before) will bounce, with or without air.
Simply wash out a pig's bladder, inflate it, and seal the openings. A proper pig bladder ball is simply material made from a pig's bladder wall cut into panels which are stitched together, then inflated. It is structurally similar to a ball made from any other material (leather or plastic, for instance).
Yes, theres soccer and basketball.
A Radar gun
You score in a soccer game by kicking the soccer ball into your opponents net from any area on the field. This is called a goal.
No this is simply to hold the ball together, it does not affect the distance the ball travels in any way.