Not feeling confident

Q: I have 3 kids but I am jobless since 3 years. I dont know whats happening with me, its kind of thinking again and again of the past and regretting. I am not confident enough to do anything. Can you please suggest some duas and amal to get rid of these situations. 

Iddat of talaaq

Q:

1. If my husband gives me 1 talaq. What is the iddat period of it?

2. Can I come again in the nikah after the iddat period?

3. Where do I have to sit in iddat, my husband's house or my father house?

4. Will 1 talaq which was sendt by post be valid without any witnesses?