Fir quash

Section 364 of IPC is a non bailable offence. Court of Magistrate can't grant bail in such cases. ... FIR and other circumstances plays a vital role in granting bail.

Yes, H.C under it's inherent power u/sec 482 of Cr.P.C can quash FIR/complaint.No don't that sec 364 of IPC is serious offence and non compoundable but where the parties have reached for settlement/compromise and on that basis quash petition is filed then for ends of justice H.C  can quash FIR/Complaint under it's inherent powers.

In the quash petition filed by the accused before high court, the defacto complainant can file an affidavit expressing  no objection to the quah petition giving reasons that disputing parties have settled the matter amicably on a compromise note.

The high court may consider the same.

If the quash petition is dismissed, then the defacto complainant may turn hostile witness during witness evidence deposition during trial proceedings which will enable the court to acquit the accused. 

Yes, the parties need to approach the High Court.

If the complainant party try to open the case again on grounds that they did not permit any lawyer on behalf of them to stand in court will hc reopen the case after disposing it and also if hc reopens the case what will be the use of the affidavit during trial