Dragon's Den... It's gonna happen

So! back to my project and I decided I'd try to re-tackle the Dragons den by freeing up some more space. 1st off, I want to list the places I'd be getting rid of in order to attempt this:

-Phoenix Cave
-Cyan's Dreams
-Zone Eater place (Triangle Island Cave[Not using Gogo in my hack])
-Hidon's lair (Not gonna include this)

If I need more space, please let me know. Now then, I can't ask anyone to jump on this FOR me, so I would like to request the following:

-information (or best opinion) on what I should start with. What's the best way to tackle this from the start?

-What all I would need? Does this require event editing? Is that how the switches and such work to navigate the dungeon with 3 parties?

-How to make the dungeon ask for 3 parties instead of 2? I remember Madsiur mentioned this in an older post about how the Dragon's den needed more than 2 parties but I myself have never played the GBA version.

-How to disable the Cyan's dreams event, the Hidon event, and the zone seeker event.

-Anything else you can think of.

I know this is a lot to ask but not doing any of this for about 2 years really gets your brain jumbled with it all xD. I would like to tackle it though and I intend to succeed and release the 1st dragon's den (or so I am aware). Any help is welcome and if I missed anything I'd need, please let me know. Thanx so much for the help ahead of time!

~Roy