Preparing food and eating in the the state of janaabat

Q: I had ejaculation last night and don't have ghusal. I have 3 questions:

1. If I wear clean clothes, do they become impure (naapak) if my body has sweat and my clothes become wet as my body is impure (naapak).

2. If I drink or eat something without ghusl will it be haram?

3. If I prepare food and wash my clothes with water in this condition will both of these things become impure if I dont have ghusal?

Zakaat on cash

Q: My question is about nisaab of zakaat on cash only.

I do not have any thing like gold or silver but just some cash. Please tell me on how much cash will I be liable to pay zakat. Will the nisaab of gold apply as cash is an alternate to gold in banks? 

Remarrying after khula

Q: I have a elder sister, she had taken a khulanama and talaq e bain as per Indian juridical in the year of 2015 and she also taken a custody of her 3 year son at the time of Khula and from now they are living separate.

Now her husband wants to remarry with her and he is saying I didnt say a word of talaq and since you wanted khula so I just signed and my intentions were not to take khula.

After they get khula my sister didnt perform the iddat period and she is just living a life without a husband.

Now they both want to remarry, can they remarry in Islamic laws.

One more thing, on khulama paper it was written that khulanama and talaq e bain irrevocable what does that mean?