Dear Querist my opinion on your queries are as under:-
1.)How long it will take and what are the chances of getting the FIR quashed.
Opinion:- within two or three hearing, the matter will be decided by the High court.
2.)What difficulties they may face even if his in laws do not oppose the FIR Quash.
Opinion:- nothing.
3.) What is your suggestion in the given situation
Opinion:- file the quashing petition before the high court based on written compromise and against the charge sheet and subsequent proceedings.
I want to understand ,can high court involve the police also for quash of FIR ?
Opinion:- yes IO will be there to verify the complainant and IO will also file his report before the High court.
2.) What they need to go for quash of (a) charge sheet under section 306 or (b) FIR under section 304B ?
Opinion:- charge sheet and subsequent proceedings.
3.) If FIR quashed in HC will the case be over in district court automatically?
Opinion:- no, a copy of the quashing order of the high court will has to be submit before the trial court.
4.) If it does not get quashed in HC then do it has any drawback for both of the parties.
Opinion:- no, there will be no draw back.