I just played the beta,
So I'll start with your questions step-by-step
1) I see your story is pretty good and I liked the memories scenes, but at some point I got tired of walking around the garden, although there were interesting choices that determined the character's personality and stats. The characters we meet at Chapter 1 are okay.
2) You give the reader the opportunity to track the change in his stats, but it loses the feeling that I really built the character's personality, and not just pumped his skills. At the time of the first Chapter, it would be worth removing the visibility of stats, just letting to the reader that his choice affects the protagonist.
3) I think you should make your demo shorter, because you have so many choices to build protagonist's stats, but you have no chance to use them in fight. As a result, you waste much time for nothing and in full game you will have to do all this again. Just show the reader that in the first Chapter he will have to help the protagonist remember his past and set his stats.
4) The most compelling for me was the thief, the least was the bard, but this is a matter of taste.
5) It depends on what you want to create in general: a novel or an RPG. Your structure will be fine if you will make more of RPG elements/gameplay for your game. The "death" possibilities need to be not predictable and in small numbers, I think.
6) I was okay about all that. The only problem is that the protagonist sighed too often at the beginning of the Chapter 1

. I liked him the most while I was making him "logical". Also there were enough of the choices, maybe you should make a little bit less of them.
In general, I liked the animated sprites and the presentation of the surrounding world to the player. I really liked the prologue, at some point I even thought that my choices can determine the race of the protagonist.
There also was a problem about the black background appearing during the sprite animations. I've never worked with animation, so I can't even guess what the problem might be. And if you want your testers to use Ren'Edit, you should let them know what it is and how to use it. At first I didn't even understand what the two buttons on top of GUI were.
Wish you good luck with the development