I am in some kind of an unusual situation and have few questions.

I am working on L1-A visa and the visa expires in DEC-2024. Unfortunately, my employer is not willing to apply for GC anytime soon!.
My wife is working on L2 visa (without EAD). She also has unused 1 year of H1B.


1) If my wife's employer applies for GC (while she is on L2) and i-140 is in pending state, can she apply for H1B extension without losing the i-140 progress?
2) If 'No', can she apply for H1B extension AFTER i140 approval without losing it's progress? Or i-140 status does not matter to change the visa type and nothing will be affected?
3) Additional questions : Will i-140 be approved only after the priority date has reached or it may be approved no matter what the PD is? Assuming we will go for premium wherever possible.
4) Until i-1485 is approved, can my wife be on H1B and I be on L1A (with extensions) without changing my status to H4 ? Will my entire family be the beneficiary of i-1485 despite the visa types?

Many thanks in advance.