how do i get all of the key s in the water temple and how do i get to shadow link

Beat the temple the cheap way.

Find ruto. Follow her to where she raises the water. Raise it. Go to the middle structure, raise the water there. Go to where you found Ruto. Use the hookshot on the symbol to get the longshot. Go to the top floor (raise the water.) Longshot to the boss room. Use the trick to bypass the boss door.

In Master Quest, if you go to the room Ruto first takes you to, the one with the Middle Water Level you go one floor below that and you can step into the next room on that floor and there is a symbol on the wall(You'll have to lower the water from the symbol in the middle structure of the temple). Hookshot it and you'll get the Longshot. Then, when you get to the Boss's Room (By raising the water on the top floor to the max), you can Longshot to the structure next to the Boss Door. Stand on top of the door, take out your sword. Hold R and side-step towards the door, press B instantly and then A to do a jumping slash attack. If done correctly, you'll go through the locked door.