Marrying a chaste woman after committing zina

Q: I got into a debate with a person who has quoted from the Quraan about the topic on fornication. She stated that according to her understanding of the verses, a fornicator, even if they have repented cannot marry a pure person and if they do then the nikkah will not be valid. I debated that Allah Ta'ala forgives the sincere repenter so how can they be punished if they go on to marry a virgin etc. Please shed some light, was I right in my reply?

Paying zakaat on behalf of one's wife

Q: One year ago I got married. My wife was gifted with gold from her parents and my parents too. The gold qualifies the "nisab" amount. She is a domestic wife. First I planned to pay zakaat on the the gold in a lumpsum after one year. But being a salaried person I could not do it as per my planning. Now I intend to pay a certain portion of zakaat from my salary each month. Please guide me on how should I calculate zakaat. For example on completion of the first year, the rate of gold was different from now.

Issuing talaaq without having knowledge of talaaq

Q:

1- Without having any knowledge of divorce by giving divorce or demanding for divorce can divorce take place? God is ever forgiving.  If we ask for forgivness, will he forgive us or he will still punish us for that which we were not aware of?

2- If two divorce were given by using word "divorce" two times just to get out of house in fight. Will those two divorce count?

3- Can Allah forgive woman in haiz if she makes some stupid decision or ask for divorce from husband and husband says divorce word two times without having intention to give her divorce and she stops him (it means she didn't mean it) will that still count as divorce?

4- In haiz, women go through a lot of sentimental and emotional mood swings. If she demands for divorce will that be considered?

5- There has to be intention of giving divorce or divorce just takes place anyways?

I have heard that God is always forgiving. Ask him for forgivness if you make any mistake. Without having intention or any knowledge, he's kind and he will forgive. He won't be unfair with anyone. Does divorce mistake not count in this?