Yes. You can play through the entire Hyrulean Adventure mode with one to four players. Some modes of play, such as Shadow Battle, are only available for more than one player. This game is a lot of fun for one player, but it gets even better when you play with a few friends.
If you're playing through the game in single-player mode, you can use either the regular Nintendo GameCube Controller or a Game Boy Advance connected to the Nintendo GameCube with a Nintendo GameCube Game Boy Advance cable. If you're playing the game in multiplayer mode, each player will need a Nintendo GameCube Game Boy Advance Cable and a Game Boy Advance to play.
Yes. You can use either an original Game Boy Advance or a Game Boy Advance SP as a controller. You must use a Nintendo GameCube Game Boy Advance cable to connect your Game Boy Advance to your Nintendo GameCube.