L2 to L1A change of status (COS)

Hello Friends,

Can someone please help in answering the questions related to COS from L2 EAD to L1A?

  1. Which forms beside I-539 to be submitted by employer ?
  2. Expected processing timeline ? Does it have a premium processing ?
  3. Will it be like the normal L1A visa interview or just the biometrics ?
  4. Can a person continue to work if L2 EAD expires but COS is pending approval ?

Thanks in advance !