Hello there. First thank you for the post and glad to know you are enjoying the demo. As for your suggestions i'll try to answer here.
1. I considered it, however, due to the way images/sprites work, doing that for every growth would be unfortunately impractical. However, there is a grow out of cloths event later in game.
2. NPC's do have a few reactions to various sizes in the game. though they aren't as complicated as for every size.
3. equipment isn't really a big part of the game so likely won't be playing a big part in it.
4. same as 3.
5. there are new moves for sizes, they just aren't in the demo yet.
6. at this time the demo is a heavily cut down version of ACT I, with several area's events, etc. trimmed. The goal is to make the game have several hours of content, or that is the goal at least.