1./3. There is a 10% discount on steam until May 2.
Early access can vary in time. Usually it’s 1-2 years for other games, but it can be different.
Familiarize yourself with the roadmap.
2.You can’t finish the game, figuratively speaking, you only see part of it. And you can go back to regions to see new enemies.
The game will improve as content becomes available.
Usually progress in games after early access is not reset.