It is highly dependent on your lifestyle. Do you go out often? Do you eat out? Do you buy car or lease? Do you want 1bed 2bed apt or so? Could be from 1k/month to 4k/month easily.
Its really hard to track it. Usuallly it comes in 1-3 months. For me personally, it took 6 weeks. Its usually recommended to stay in the country before you get your physical PR card.
Ye, think about it realistically. You get offer with clear instructions, even without some information exchange or set of interviews. Who would do that?
Does anyone know the approximate topics discussed and requirements during the interview? I also understand the interview takes place almost in the end of the whole process?
Then once the landing duties are due, and you have a strong reason to move because of the job offer, I dont see any problem with that. Also, make sure you double check the requirements for FSW-O in your case.