You would not be eligible for adjustment until your spouse becomes a USC.

Yes this divorce will impact your eligibility for citizenship.

Your friend should apply for a student visa to study in the US.

Yes typed and handwritten forms will be accepted.

You may refile but should understand why the 1st case was denied before doing so.

Wait for approval or depart prior to decision.

Yes child support may be counted towards your income.

Your sister can apply for the tourist visa on her own.

Yes there are two affidavit of support fees with NVC.

Best to have an attorney review your entire file to provide guidance.