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?

Earning through doing class assignments and exams for people

Q: I have a question regarding one domain of modern day freelance work. People contact me through the freelancing website (where I have my profile made that mentions the subjects that I'm expert in) and ask me to do their class assignments and projects. Sometimes, they also require help on their tests and exams both online and inside the class. We decide a price with mutual consent and I get paid once the work is delivered.

Now I have a couple of questions:

1- Is this mode of earning permissible?

2- If not, then what about all the money that I have earned and spent on myself and my family till this time and this amount will turn out to be not so little as I've been working in this mode for last 2 years.

3- What about the profits and investments in the property and other traditional businesses that I have done using this money that I have earned from the above mentioned work mode?

4- What about the savings that I have in hand for the time being?

Doubting whether wetness is mani or discharge when waking up

Q: I got up and noticed wetness but as I was having this kind of discharge most of the time nowadays and before sleeping there was some discharge, so I didn't do fard ghusl and read fajr and recite Quran. But I was feeling like I was sinning as the amount of discharge was not this much before sleeping and on the other hand it was like normal discharge which I was experiencing normally. Now is my salah valid or not?