Dynamaxing uses the same logic as changing form mid-battle, which reupdates the stats and ability of the Pokemon. This needs to happen, since its possible for someone to make a custom G-Max or Eternamax form that has a different ability or stat spread from the base form of the Pokemon...
Yes, it is. The coordinates are obviously designed for the default UI.
The base numbers aren't 4, 0. They are @spriteBaseX + specialX + 4, 0. The X coordinates are calculated based on the bitmap base and then adjusted based on which side's databox its on (foe, player). Since youre using a...
Theoretically, I suppose. The Trainer Intro plugin does this, so you could emulate a similar behavior here. Youd probably have to change a lot, though.