H4 EAD employment eligibility when primary H1B is out of USA

The scenario I have is :

  1. Primary H1B holder has a valid H1B visa and I94. Also I140 is approved in EB2. There are direct reports under him.
  2. H4 EAD is employed in USA with valid EAD and I94.
  3. Primary H1B holder travels outside USA as requested by employer for a year.

Question :

  1. Can the H4 EAD continue employment when the primary H1b holder is outside US (with valid H1B)?
  2. Once H1B holder is back in USA can the petition be upgraded to EB1 from EB2?