1) is this an arrest stay for 30 days?
It can be construed as stay for 30 days within which you should utilise the option to get enlarged on bail from the concerned magistrate court.
2) if not, what does it mean? does it provide any relief to me?
The relief is there in it that though the quash petition has been dismissed you are given an opportunity to get enlarge on bail within 30 days, which indicates that the police cannot arrest you within the said period.
3) Can she add 376 to the FIR now and make this judgement irrelevant? (she has mentioned 376 against me and my brother in her statement)
She cannot do so now since she has already included the ingredients i her complaint bu the police have not take cognizance for that offence. She has to apply before magistrate court a petition for re investigation and to include the same by invoking section 173 (8) cr.p.c.
4) if she can, what would happen? what do you reco overall basis this case?
After following the procedure she has to prove before the court as to what is the reason for inclusion with documentary evidence for those charges. supporting her claim.