485 current, should I move?

My I-485 (EB2) is going to current in Sept. I have some questions as I am now planning to relocate to another state:

1. When will they send Ref. request if need, right after I-485 is current or after they exactly touch my case. If I don't change my address, will it reduce the posibility of getting a Ref. request about employment status? (my background should be simple. F1-H1B, 3 years work in the first company and another 3 years with my current one, which sponsor my GC application.)

2. Will they send Ref. request to the employer directly or send to me? Assume that I get Ref. before changing the job, and my company responses it already, then can I leave for another job and relocate to another state before getting GC? usually how long will GC be approval after Ref.

3. My 485 receipt no. begins with WAC, now forward and pending at TSC, whether these kind of case are slow for approval? If I have to relocate, is it suggested to do sooner or later?

Thank you