1 - You collect red coins.
2 - You're collecting some form of star (shines).
3 - You need certain amounts of shines (stars) to activate particular events. (They just don;t tell you how many.)
4 - You can get 100 coin shines.
5 - Its run on Gamecube, a 128-bit machine.
Andy: Like Super Mario 128? The number after is doubled! ;D
Kenn: Oh shut up about that dumb glitchy Super Mario Sunshine, you dimwit. It'll never be what Super Mario 64 has become.