Thank you for your report!
Can you please specify a bit more about those issues?
What is the OS you are using? Is it Windows, Linux or Android? What version?
Crash when going to the next level - I’ll investigate that. How often does that happen? How the crash manifests - you have some error message shown on screen or the game just closes or freezes?
Errors in start with 2 characters - does this happen on level “zero” or on deeper levels? On level zero (the settlement) - it’s intended. Every character rescued from the dungeon goes to the settlement and you can chose which one to control from Pause menu, there can be many of them. Other characters don’t have AI right now, but in future you’ll be able to take more than 1 character on some missions.