I have an approved I-140. My priority date is April 2011. Can I file for EAD on the basis of approved I-140?

My wife is in F-1 visa status (cos from H-4) and I am on H-1B (I-140 approved). She needs to travel to Canada for an academic conference and she doesn't have stamping on her passport. Can we apply for visa stamping in Canada?

Changing their employer from Company A (Current Primary Employer) to Company B (Direct Client of Company A - which will be the new primary employer going forward) - Can the experience earned by the person (skill set as well as number of years) earned with Company A be used for satisfying the job requirements of PERM / I-140 petition filed by Company B - if the person was actually working for the direct client i.e. Company B - all the time while employed by Company A (Current Petitioning Employer for approved I-140) ?

After getting GC (emp based):<br>
1. If an employee is working for an end client (employer - vendor - end client): while employed with GC sponsor, can a person be on bench (no pay) for some time? or like H-1B, it's considered as out of status, risk of GC revocation? <br>
2. Would like to travel to visit family abroad- At of POE, any questions by the officer ? Even though still employed, but not on a project at end client?<br>
3. While applying for citizenship later, if W2 < LC salary for any given year, negative impact during interview?<br>

4. Also, as a green card holder, can a person be self-employed(sole owner of LLC - and do 1099 contracting for US clients) ?<br>
5. In above scenario, is it legal if you(LLC) did not make any revenue in between contracts?<br>
6. Is it legal for GC holder to be unemployed, or like H-1B, if you are on bench or not getting paid by employer - you are out of status - hence risk of losing GC?<br>