Type D visa

Visa D will give you the right to come and go in Bulgaria indefinitely for the period of the visa. Also with visa D you can apply for prolonged stay permit. Without visa D you can stay on Bulgarian territory 90 days for every 6 months.
If you have more questions regarding visa D, permanent residence, or citizenship feel free to ask, I will try to help with information regarding different procedures.

If you are a US citizen receiving your benefits based on your own work record (not on your spouse's) then you are eligible to continue receiving your payments (by direct deposit) in Bulgaria, whether you are a resident or become a citizen. It gets complicated if you are not a US citizen or if you are receiving benefits based on disability or a spouse's work record.

The two places to check:

https://www.ssa.gov/pubs/EN-05-10137.pdf   (This gets a little confusing with all of the recipricol agreements, but in the first few paragraphs it basically states that if you are a US citizen and residing in another country (except North Korea or Cuba) you can continue receiving.

And this:

https://www.ssa.gov/international/payme … ideUS.html

Super helpful for determining your specific situation.

The last requirement on my list of things I need to take to the Bulgarian Consulate in LA to get a long term visa D is I need to get a Rent contract of a house/apartment in Bulgaria and a written consent letter by owner of the house/apartment that applicant (me) would be living there. (I would be looking for a place to purchase in or near to Blagoevgrad once I get there).  The consulate officer also told me that the letter would need to be notarized and mailed to me so I could deliver it to them.  I need to know what the contract and letter should say so I can ask my friends for help.   I have questions on filling out the application, but will work on that once I get this housing issue started.  Thank you for any help