My out of country partner and I, are ready to get married and file for his green card. Any 'same sex marriage' expert lawyer?

It does not matter what state you hire your attorney in and any immigration attorney should be able to handle same-sex marriage petitions. Good luck.

What should i select, petitioner or principal applicant? while filling for AOS processing fees.

You would be the petitioner in that case.

I need to know how to answer the below question that i have received in the Request for evidence (RFE for my L1B visa extension.

This question is not appropriate for this forum. Schedule a consultation with an attorney.

Complete G-639 FOIA request for such records.

I have overstayed on a visa waiver, can I go home before a 6 month overstay and apply for a work visa, if not can I get a k1

As long as you leave before 6 months of unlawful status you should be okay. If your fiancée is willing to petition for you, this is a good option...

When do i file i-864?

You file the 864 when you are submitting the adjustment of status application.

I applied for ilr visa and it was refused and in second hearing home office withdrawn the hearing what happen next pls help me

I'm not understanding your question. Please rephrase or schedule a consultation to discuss the matter in person.

H1B transfers generally require more than one month of pay stubs but you should confirm with new employers attorney.

Can i travel outside us while on removal proceedings?

No, traveling outside the US is not permitted while in removal proceedings.

After a Notice to appear cancelled, what should I do to adjust my immigration status.

If you are EWI you cannot adjust your status. To explore your options I would recommend consulting with an immigration attorney.