His mechanic is:

He'll slowly come to the office through either the left hall or the right hall.

When he leaves the Generator Room, you have to find him on the cameras and flash him several times to reverse his progress.

I'll also show the mechanics for the other 3 animatronics:

Jack-o-Bonnie: He'll come to the office through the left hall. When he's on the doorway, flash him several times to make him go away.

Jack-o-Chica: She'll come to the office through the right hall. When she's on the window, flash her several times to make her go away.

Dreadbear: He'll come to the office through the left hall. When he enters the office, put on the mask.

Now, about the star system:

It works like on the other games. On the main menu, the stars are, from left to right:

1. Beat Night 5

2. Beat Night 6

3. Beat 4/20 (Golden Dreadbear) mode

4. Beat all Custom Night challenges

5. Survive for 10+ minutes on Endless Mode on Golden Dreadbear mode.

On the Custom Night menu, there'll be stars on the challenge name to show you've beat that challenge.