I got married after filling in N-400 form for the citizenship. So will there reject it?

No, you can simply tell them at your oath ceremony.

I got a letter from USCIS asked for assists or joint sponsor because my petioner(wife) didn’t meet the poverty line.

Yes, you can use mom's income and include an I-864A, along with proof of her status and income. She does not have to independently meet the poverty...

Can I apply for green card through my US born wife where her father's name is spelled incorrectly on her birth certificate?

Yes. Her dad’s incorrect spelling will have no impact on your case.

Can my parents, who hold A2 Visa status, obatin a green card through their child?

Yes indeed, it appears they are eligible. No blue list; you were born a US citizen.

Yes, there are no issues with hiring an attorney for this reason.

Can I still get daca parole now that trump eliminated daca? Mine is still good for another 2 years

No, unfortunately that opportunity ended. You can no longer get advanced parole based on DACA.

I would not be worried, simply prepared. You need to be able to articulate why your families do not know. For example, I represent many same sex...

What do we need to do as my husband's 1 year extension for GC is about to expire in 2018 and 1-751 hasn't processed yet ?

Schedule an infopass appointment and he will be able to get his passport stamped extending his status for another year....

Do I need to submit application for Advanced Parole even though I have a valid F-1 Student Visa?

Absolutely. If you leave prior to receiving advance parole you will have abandoned your I-485 application.

Can my husband file out form I-130 for me and my children (17 &14 years old) together ?

As my colleague stated, your husband would need to file an i-130 for each one of you as he is an American Citizen.