How soon to file EB1 before I94 expiry when on L1A?

[buzzpriyav]

Hi,
I am on L1A in USA and my I94 is expiring on Dec 10th, 2015.(will be completing 7 years in US by then)


My company is planning to file GC - EB1 category.

1) How soon they should file GC EB1(I140, I485 and EAD) for me? Can they file 1 month before my I94 expiry?
2) Can I stay in USA (without working) after I94 expiry when my I140 and I1485 and EAD are still under progress?
3) What is the minimum period that my visa shuld be valid before my company can file for GC? can they file the day before expiry or shuld it be couple months in advance?

Kindly help

Thanks in advance.