I am in AOS(I-485pending for over 30 months) with I-140 approved in December 2007. I am planning to invoke AC21 with another employer. I just found out that salary mentioned in Labor Certificate was 80k and in I140 application was 85k though i am currently paid 75k.

Q1) Will this wage difference cause a problem for I485 approval?
Q2)Legally should the salary mentioned in the Labor and I140 match my current salary?( I am using a substituted labor)
Q3)Should i ask my employer to pay the salary difference to be on the safe side?
Q4)Will this wage difference cause any problem if i invoke AC21 and if my new employer agrees to pay 87k per year? What precautions should i take if i decide to go with AC21 with new employer?

Thanks