Controlling the characters specially humanoid is very easy in unity if the rig is correct . Unity provides a humanoid avatar and mocap library for basic animations . These animations can easily controlled using the mechanim which is unity’s animator based state machine .
For the second thing , in unity , a level is very equivalent to scene and yes the same if logic can be used to load the scene when user accomplished something .
I might have used some keywords in unity context , if you didnot understand something just search these keywords which will help you to understand more about them .