No, there are no cheat codes in the game.
No.
defeat Zelda
defeat ganon
When you get it laying on its back in the water, press and hold B (as you do for the shadow beings) and release to hit all the legs at once.
it's easy all you have to is turn wolf
as soon as you defeat the Minny Boss in the Forest Temple you get the boomerang
I'm not exactly sure of what you are talking about, but the thing I think you saw was a Poe you can defeat these by using your senses as a wolf. I don't think that you can defeat this poe at this moment until you get the ability to transorm into a wolf at will.
To defeat the demon ghost in the Arbiter's Grounds, wait until it turns solid, then bite the crap out of it.
collect all the monkeys then defeat the flower boss
she does. Defeat the 20 monsters then she gives you the charm.
You don't get the mirror shard from a chest. You have to defeat a boss to get a mirror shard.
You can fight him as many times as you want.