H1B to L2+EAD

[SamirSanghavi]

I am currently on H1B visa in US , My Spouse is on L1A visa. I plan to move to L2+EAD ( for greater flexibility) and use my remaining H1 time later if required.

I had following questions

1) Can I remain in US while working on H1B and for L2 and EAD application is still pending approval ?or do I lose my status as soon as L2 is approved by USCIS?

2) Once I receive L2, do I have to leave the country for COS to take effect?

3) Once my spouse's L1 status runs out ( about 4.5 years), how does move back H1B work? Do we both have to leave country and reenter?