First few runs - Need some tips/Introduction

I've been browsing the site for a couple of weeks now while I was playing OOT for awhile, and then I noticed the speed run times for my favorite childhood game.

After watching bits and pieces of Krystal's run and a couple races I decided I'd start to play the game again.

I've made four runs so far, the first three on the gba version and then I moved to JP 1.00 to see how that would go.

The first was a bust 100% run, I shaved almost two hours off doing 100% on the second run and at this point I know I could probably drop another hour.

My third was any% and I grabbed some extras along the way, made some stupid mistakes such as not planning out getting both the flippers and the medallion at the same time, so I made two trips up there.
I also died 3 times, having to start at the beginning of the dungeon.

My fourth was better, however I know I can drop that time by a lot.

I was just wondering if I can have some tips based on what I know wasted some time here and there:

- I can't for the life of me get done with the castle escape in less than about 6:30 even with skipping everything but the boomerang. I move relatively quickly in all rooms.
- In the Eastern Palace I am able to get only 3 skeletons to spawn, however I can't quite figure out how to quick kill the first two and despawn the others.
- How much time is wasted each time you hit a wall while running, I'm getting better but I still am hitting walls in places
- How in the hell do you kill Moldorm in a timely manner?
- Tips to save time in boss fights and also avoid dying (Particularly Arrghus and Vitreous)

That's the main few questions I have. I just can't seem to move through the light world as quickly as I should, I have about 15 minutes of time wasted. I also end up back tracking
because I don't have a solid knowledge of the routes, however I've been following the general route taken by Krystal. I've been adamantly watching some runs to get a firmer grip
on the game.

Here are my times for my first four runs (I timed based on the rules presented on the leader board):

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Run 1 - 7:37:14
Run 2 - 5:41:06
Run 3 - 3:49:22
Run 4 - 3:22:44.934