Please, correct the sentenses I wrote, If they are wrong.

1. I will write down your telephone number for the purpose of not forgetting it
2. He have a habit of waking up early
3. He entered the room without knocking at the door
4. He was awarded for saving the life of his friend
5. I prefer living at the north in summer
6. You very helped me by giving your records
7. Have you succeeded in finishing his work in time
8. I haven't any objections to going there to-day
9. I stand for sending them a telegraph right off
10. Don't you mind my reading this story aloud
11. He objects to the meeting being appointed on monday
12. At one point there is a small cross done in the red ink and above it there is "3.37 from left" done in faded pencil writting

And one more question about prepositions. I read in two different grammar books that I can say both -
1. I work in a factory
and
2. I work at a factory,
the first book saying that "1" variant is correct and the second - that "2". Which variant is right?

Thanks in advance!!!