barevfamilyman

This is the template I used last year to successfully make the request on the NVC Inquiry portal. I uploaded all evidence showing that the beneficiary had resident status in the new country and was currently living there. I would err on the side of uploading too much evidence that shows residency in the country.

change of interview location request template.doc

You can make a request via Ask NVC inquiry: https://travel.state.gov/content/travel/en/us-visas/visa-information-resources/ask-nvc.html

They will want to see evidence that he is a resident of the Dominican Republic, so probably something like a Dominican resident card or whatever documents he has that show he is a resident, and not just visiting.

When I made my request to change embassies, they also asked for a signed letter. I have attached the template I used to successfully make the request.

change of interview location request template.doc

According to the State Departments immigrant visa process website it may be required. It's probably a good idea to have it prepared and bring it with relevant evidence to the interview in case it is asked for. 

https://travel.state.gov/content/travel/en/us-visas/immigrate/the-immigrant-visa-process/step-10-prepare-for-the-interview.html

4. Public Charge Questionnaire: DS:5540

You may be asked to present a completed DS-5540, Public Charge Questionnaire, and supporting evidence at the time of your interview. To prepare that documentation in advance, please visit the DS-5540 Public Charge Questionnaire page of this website.

I think I would handle this differently than the above poster. I would put the day you intended to get married and stay in the US, that is, the day you made the decision to adjust status and not return to your home country. If you were intending to go back to your home country, and then later decided to get married (which it sounds like is the case), then can you really say that the US address was your address before it was your intention to get married and stay? It was really just the address you were staying at. 

Some clarity for the transition to consulates implementing the new DOS rule quoted from https://fam.state.gov/fam/09fam/09fam030208.html

Quote

(5)  (U) Informing Applicants of Required Documentation: Post will necessarily process some cases that were documentarily qualified by NVC or KCC prior to the effective date of the public charge rule or without the DS-5540.  To help ensure a smooth transition, you should make every effort to inform applicants in advance of the visa interview of supporting documents that will help you resolve a public charge determination.  This could include a request that applicants complete and upload the DS-5540 to the CEAC, or bring it with them to the interview.  Posts may also request applicants bring with them to the interview supporting financial documents or other documentation post knows would be relevant.   Ideally, you should be in a position to assess whether applicants are ineligible for visas under INA 212(a)(4) at the end of the initial visa interview, assuming that the applicant has made reasonable efforts to submit the evidence originally requested.  Applicants who you determine are more likely than not to become a public charge at any time after admission even after the presentation of additional evidence, should be refused under INA 212(a)(4) instead of INA 221(g); however, you must provide applicants an opportunity to provide a completed DS-5540 before you refuse an application under INA 212(a)(4).  Adequate time and effort spent prior to and during the initial interview can save work for the post and the applicant in this respect.

It sounds like all interviews starting today will, even if DQ'd before 02/24, will be subject to the the new public charge rules