L1A - H1B - 6 years expiry etc

Friends,

Have few questions and hoping experts here can help -
Myself -> Worked in US on H1B and have approved I-140. Now working in China and coming back to the US on L1A. Two questions -
1) If for any reasons I want to change employer few months down the line, can I change from L1A (current company) to H1B (new company)? Do I have to go through the H1B quota?
2) How soon can I apply for green card after I receive my L1A and how long would it take (on average) to receive Green card from application date?

Spouse -> Worked in US on H1B, exhausted 6 years and then moved to H4. Perm applied in 2013 and I-140 applied in 2014 and awaiting approval (expecting in next couple of months). Two questions -
1) If Spouse goes back on L2A (no job yet) and applies for EAD, how long (on average) to receive EAD approval?
2) If Spouse goes back on L2A (no job yet) but finds a job with an employer ready to sponsor H1B, does she have to go through H1B quota or would it just be an extension of her old H1B?

Appreciate any clarity you can provide on the above questions.

Regards