EAD Questions
1. i don't know the answer to this one. hopefully i think anywhere from 14 to 90 days.
2. Yes, you can do as many part time jobs as you want. below is text from the FAQ section of this site:
Who can I work for after I receive my EAD?
Persons who receive an EAD as part of an adjustment of status application may work for anyone. The grant of employment authorization is essentially unlimited. There are no restrictions on whom you may work for or how many hours you may work.
3. Yes, you will be working at your sponsoring company using your H-1 unless your employer files another form to use your EAD as authorization. In most cases, I think your sponsoring employer continues to use your H-1 in most cases. EAD simply grants you permission or rather allows any other employers to hire you legally.
this is another pasted text from the FAQ section:
Do I have to continue working for my sponsoring employer?
If you are an employment based AOS applicant, you must continue working for your sponsoring employer to retain your eligibility.If you take a leave of absence, the burden will be on you to prove that you will return to permanent employment with your sponsoring employer. If you wish, you may also accept additional employment with other companies, or even open your own small business. This additional employment must be supplemental to the employment used to qualify you for adjustment of status, however. Family based immigrants and dependents of employment based applicants may work for anyone.
I hope this helps.