1. There can be 12 NPC's in any given map. The reason for this is because it is all the Movement Events will recognize, 12 NPC's and 1 Player.
Ah, I see. With that in mind, my idea for using one of the crystal rooms (Tower or Lunar) should be feasible at least, if they're different maps!
2. Yes. There can only be 255 NPC's in the Overworld and 255 NPC's in the Underworld/Moon due to how the visibility flags are set up.
That's actually a much higher number of NPCs than I thought would be available per world. Since I'm nixing most of the dancers to attempt a party-switching system, I should at least a little room to play around with. Hopefully haha.
3. As far as I recall, there is not. If you use Shift and the direction buttons, you can create a square in which you can replace a square of any size with any given Single Tile. I do not believe copying was ever implemented though.
I actually happened to figure that one out as I was working on Kaipo earlier! I also realized spacebar is a "fill-in" option when I at one point accidentally turned all of the sand into wall tiles lol.
As for your Kaipo idea... you may want to test that after you've finished the Edward event there. If it still works fine, great! If not, there may be a reason why those are there.
There's a bit of working around I need to do, but for the most part it works alright. Since at one point, the event loads the Black Room for the "That Night..." message, I'm going to have the end of the event transfer to the Overworld outside of Kaipo.
The thing is, if I go by the X/Y coordinates in the trigger info, I end up waaay off course (halfway to Troia instead of outside Kaipo). i'm not exactly sure why, but with some trial and error it should be good to go!.
EDIT: Got it! using X125, Y105 for the coordinates transfers perfectly to one tile down from Kaipo on the world map! Now the player won't be warped to the Inn or Hospital when leaving town after the "Rydia Joining" or "Curing Cecil" events.
I also feel like I've got a grasp on how the game handles the two trigger types for map transfers (Dot and Arrow). Seems the game stores the data for the Dot triggers in a stack fashion, so touching an Arrow trigger afterwards takes you back to the last map you Dot transfered from. so if you use Dot trigger, then try to go to the Overworld by walking past a map's boundry lines, you end up back in the map you Dot transfered from.
Somewhere on this site, Grimoire and I pondered this one. You seem to have gotten some of the ones we hit on, and a few we didn't. Another big one you didn't mention is the Tower of Bab-il crystal room. The map is complete (has a back wall and full detail throughout) but the player never sees north of the eleventh row or so (under normal circumstances, because of the trap door event). You can blank the whole top half out and save somewhere around 300 bytes (yes, bytes, BTW).
As far as the way the data is written affects the amount of space used, you get, essentially, one extra byte for every consecutive tile of the same kind. So adding the extra trees in Baron saves space because you're normalizing the path (and the secret area?) With the rest of the map.
The map data is written out tile-by tile from the top left to the bottom right, except it has the ability to say up to "255 of" any given tile. So instead of (for example) "trees, five of field, ten of tall grass, three of secret passage, fifteen of trees," you made it so it just says "thirty-four of trees." The former requires nine bytes. The latter only requires two bytes.
Oh boy! I wonder how many bytes I'll get back when I get rid of the Tower's crystal room entirely? Seeing how my free space skyrocketed from 617 bytes to 1100 something bytes when I deleted the Kaipo map, I imagine I'll have an extra 400-500 to play around with!
Also, I kept the secret area, it's just not so secret anymore haha. I moved Cid's well to the middle of town where the Training room building used to be, then put a little walkway where said well used to be, turning into Cid's backyard. Hidden items are still there of course, and anyone who had no clue of the old secret path in the trees (I was one of those people before FF4kster haha) can find a few more items to keep them alive.
