Can I study in graduate school on H4? What about H1-B?

You can study in H-4 status. You can also study in H-1B status assuming you are maintaining your H-1B employment as well.

G325a - address for last 5 years - do I need to mention all the US trips for my parents within last 5 years ?

A temporary visit typically does not involve a change in residence. You need to discuss the details surrounding these visits (i.e. the duration,...

As long as you are only working for your current H-1B employer, your former employer can keep paying you if they like.

You do not need to copy all the pages of your U.S. passport - just the biographic page.

Am on an L1-A visa valid until end '16 but may resign from my job. How long can I stay in the country after my last day at work?

Your status is tied to your employment - once you stop working, your status terminates with no grace period.

Can I do a COS for my spouse as a dependant (from L1 to L2 ) while my GC EB1 is in progress?

Yes your wife can change her status from L-1 to L-2, while you are in the permanent residence process.

After L1b blanket expiry, can file L1b Blanket again or L1b individual?

There is no rule regarding applying via blanket or individual - that is up to your employer and their immigration counsel.

Can H4 dependent ( dependent of H1B) stay in US with an "Additional Evidence Notice" received for I-539 extension from USCIS ?

Your dependents remain authorized to be in the U.S. while the petition is pending - even if an RFE is issued.

Is it true if my boyfriend marries me and fix me papers he wont be able to fix papers to his parents?

Your boyfriend can sponsor both you and his parents. The issue is whether his income will support the affidavit of support requirements for all of...

Naturalization and citizenship,n400

Yes, you can send a money order. You can find the filing address on the USCIS website (www.uscis.gov) under the Forms tab, N-400.