Which word to use, which word to leave out 6 sentences?

Could you please help me make these sentences grammatical?

1 The little time I have left, I don't want to spend (it) at school.
2 Christmas luckily fell (on) my day off this year.
3 If you walk in the door within 10 seconds of the last person, the door won't close.
4 We make/have the same salary./Our salary is the same.
5 He'll be impossible to find if he doesn't want to be found./It'll be impossible for us to find him if he doesn't want to be found.
6 It doesn't matter if he doesn't have/hasn't any money.

Thank you