How Immigration Status will effect after Divorce?

I order to remove conditions on your greencard, you would have to prove that you and your husband entered into the marriage in good faith.

EAD and I-485

Only if your priority date is current.

My wife worked on EAD based on L2 status with her EAD expired in June 10.I converted to H1 with hers to H4.Can we renew her EAD?

H-4s are not eligible to work so you cannot renew her EAD.

H1b transfer with I-140 approved

Based on the facts, you may be eligible for 3 year H-1B extension.

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Received I-140 Approval Notice of Action (EB3)

You can't file application to adjust status unless your priority date is current.

Can you please let me know if i can be on Maternity leaves on L1B visa in US?

I agree with my colleague. You need to talk to a lawyer rather than the company.

Should we apply H4 renewal while H4 to H1 Change of Status is applied?

You can continue to stay in the US while the COS is pending. You need to talk to an attorney.

Visa stamping through Consular processing @ US consulate in Canada

I agree with my colleagues.

If I leave US on H1, can I come to US with L2 and file only for H1 COS without stamping?

COS to H-1B is possible. No need to get a stamping.

Can a L1B Visa which was cancelled without prejudice be converted to H1B?

No it cannot be converted to H-1B.