I am on an F1 visa studying in the US. I am from England. Would it be a problem if I proposed to my girlfriend in England?

You haven't provided much information. What is the citizenship of your girlfriend ? If she is not a U.S. citizen or permanent resident, on what...

Can l2 and ead simultaneously by myself when company files my l1 extension before l1 is approved ?

While you can file the L-2 extension with the L-1 extension receipt notice, it is better to wait until the L-1 extension is approved.

This PERM denial does not affect your previously approved I-140 - you can still use it to extend your H-1b status. As Ms. Sharma stated ,...

H1B revoked. Worked while the new petition was pending. Approved new I-797 in hand.

Yes - you remained in the U.S, out-of-status, after your H-1B was withdrawn, and may have been unlawfully present, if in fact your H-1B was...

Is a Japanese citizen who holds an E-2 Visa considered a "permanent resident alien?"

No, a permanent resident alien is a green card holder.

About to marry U.S., my visa expires the end of March, will I have to go back to China if I haven't obtained green card yet?

Depending on your particular circumstances, you may be able to remain in the U.S. while the green card application is pending. You should work...

As a green card holder, you can take as much time as you like.

What are the options for my in-law on B2 visa but overstay US by accident?

As you point out, your mother-in-law is already out of status, and unlawfully present. In this situation, there really isn't anything you can do...

Is the USCIS is the one who give schedule for biometrics after they recieve the documents for Adjusting of Status?

You will receive a separate appointment notice in the mail for biometrics.

Is it true the wait for some petitions is almost 100 years?

100 years is a bit of an exaggeration. The Visa Bulletin is the right place to look to see how long the backlogs are for certain categories.