Thanks for the feedback! I will give insight to your suggestions.
First, there will be a slider for how many levels you want to level up. That won't be too necessary though as you probably won't have much resource to upgrade more than a few levels when resources stop being unlimited
Second, the game is not fullscreen and doesn't have an option for it currently. This probably happened because the base resoultion of the game is bigger than your monitor size. If you click the maximize button that should make it snap.
Lastly, the 11th character is unpullable. You should have received her upon account creation. There is an issue that stops you from getting her if you had already created an account before this demo, but that won't be a problem after next release, as all things will be wiped.