Hey there!
Thank you for your fantastic review - I enjoyed reading it! I'm loving all of your speculation and I'm looking forward to the full game coming out so you can see what's right and what's wrong.
To answer your questions:
1) The final game will be over 300,000 words with all routes.
2) The prequel with the Speaker doesn't have a specific length yet, but may be between 20-40,000 words. It will also be free.
3) The answer to this is a spoiler, I'm sorry! You'll find out in Leos' route :)
4) Spring Bloom isn't in the extended demo, so currently isn't accessible! You'll be able to access it in the beta (if you have access from Kickstarter or Patreon), or in the full game.
Again, thank you for your kind words! It means a lot to me that a story I care for greatly can reach other people how it reaches me.
Kind regards!