None, they're all curved. A classic football (seldom used anymore) has 20 hexagons and 12 pentagons. The current Adidas Jabulani has 8 panels.
A soccer ball is a sphere and, as such, has no edges.
There are 8 3D panels on the Jabulani.
On a soccer ball there are 12 pentagons and any practical number of hexagons that can make the soccer ball look spherical.
There are very many designs for panels on a soccer ball.
depends on the ball
The best soccer ball is very well debated. Many people say it is the Jabulani is the best but some soccer players complained about it during the world cup because it would curve unnecessarily. Thus different balls were created for different styles of play. So what ever your playing style is, you may think certain balls are better than others. So the best ball for play may never be known
There are not many pieces of equipment that is needed to play street soccer. All that is needed is a ball, space to play and people to play with. Goals are nice but there can be homemade ones.