How long does it take to remarry with another alien after divorce?

There are not US federal laws restriction marriage. You need to review the state law.

MY I130 IS APPROVED. ALSO, MY HUSBAND IS CURRENTLY ON H-1 AND I AM ON H-4. CAN I FILE I-485 FOR BOTH OF US? WE IN USA NOW.

If the priority date for either the I-130 or the I-140 is current you may file for adjustment.

Can i seek assylum

Asylum is possible if there is a well founded fear of persecution past or present based upon one or more reasons - race, religion, national origin,...

Can I apply for F-1 visa while I have been placed in deferred action for U visa ?

With the U visa you have indicated an intent to remain in the US permanently. As an F you must have the intent not to remain permanently in the US....

After 4.5 years of marriage my wife divorces me , I have got my green card with this marriage. Is my citizenship in jeopardy ?

Divorce alone does not affect your eligibility to naturalize.

What my wife will do?

Obtain a re-entry permit for her before departing as well as maintain ties to the US. Repeated trips the US are also good

H1-B transfer question

As long as you maintain valid h1B status multiple petitions and employers are permitted.

As my colleagues stated be prepared for RFE's. make sure you are in full compliance and maintaining status

If i move to H4 from H1B visa, will it be revoked? Is there any chance that i can get back to H1B when i join back to work.

Yes you may switch to H4 and back to H1b

I am married with Permanent resisdent girl in USA while i have an asylum pending case. I have final hearing on 26 feb 2015.

Call an immigration attorney as soon as possible. While you may have a very good reason for seeking asylum, they are very difficult to have...