When you beat the game its over and you cant keep playing.
Yes you can keep playing but it wont be so much fun collectin piece´s of heart. Belive me it was boring as hell
Yes it will save, and gameplay will not be affected at all. the save button will stay after beating the game.
^^Well, I don't know about that, it doesn't in the Wii version so I doubt it would in the GameCube version.
You can't save after defeating Ganondorf. Loading your save file again will take you at the last time you saved prior to the battle. So, yes, you can continue playing after you beat Ganondorf.