RFE ON my I 485

[Sunayan]

Gurus,

Recently I had received RFE on my I 485.

RFE is : provide a currently signed and dated
employment letter on official letterhead.

I have my EB2 labor and I 140 approved through company "A" in FEB 2007. AOS applied on Aug 2007. H1 visa has expired. I did not extend it since I 140 was approved.

I changed the employer from "A" to "B" under AC21 well after 180 days of filing of my AOS. I did not inform INS that I changed the employer.

I'm with company "B" with salary $4000 less than what mentioned in labor application. ( Prevailing wage)..

Now ,

1) how serious is this RFE?
2) What happens after we reply to RFE? Will there be another RFE ? e.g. if we provide the offer letter , will there be another RFE saying ,give us the tax papers of the employer? etc...
3) In order to provide an offer letter , what would be bset - to give one from company "A" or "B"
4) What will be the issues if I provide an offer letter from company "A"
Will INS ask for financial details of company "A" after I provide the offer letter..

Any guidance is much appreciated...

Thanks,