Ramadhaan & Fasting

Will one receive the reward of fasting in Zul Hijjah if he keeps qadha fast in the first 10 days of Zul Hijjah?

Q:

1. If a person has fasts pending for a vow that he has made without him having specified the date, can he fast these fasts of zul hijjah or should he keep those fasts first?

2. If he has to fast for his vow in these 10 days will he acquire the sawaab of the zul hijjah fasts? Also if a woman fasts ramadaan qadhas in these days does she get the sawaab of zul hijjah fasts?

Qadha for missed fasts

Q: If I have not kept many fasts without any valid reason in my childhood, when I became baligh how do I fulfill it? Do I have to make kaffara? What is the kaffara and what if the amount of fasts is so many and I don't remember? 

Breaking one's fast due to illness

Q: I am able to fast though I am not in good health. Lately I am suffering from bouts of fever for no apparent reason. I know that fever means that I have to break my fast. If I develop fear say an hour before Ifthaar, how long can I postpone Ifthaar and how close to Ifthaar can I break my fast so that my fast would still be valid for the day?