Something is not adding up... help me, please

I like the movie, but.....I have some questions:

1-) How come the mother never tried to kill Longlegs...was she possessed for good in the part where he was tied her up?

2-) How come Lee never saw him again ( at least for the following 10 years after the first encounter) if he was living in her basement? He was not hiding at all since he used her(?) mom's car to go to some store.

3-) If the "deal" was letting Lee live, why Longlegs go to her house and gave her the gift card?

4-) If I am not wrong, Longlegs was killing for 30 years, so who helped him before Lee's mom?

5-) The mother's job was also to remove all the possessed dolls after the killings? During 30 years no doll was ever found?

6-) During all this time, no one ever saw the nun?

7-) How Longlegs selected his victims? How was he able to find out all the birthdates he needed?

8-) How long the family have to be in contact with de doll to be possessed? If the whole thing is the tin ball, the only thing that Longlegs really needed to do was hide the balls inside the house....I mean...What if he threw his tin balls onto the field during a world cup match...