No. Letters need to be from someone who can assess your clinical skills. Since PhDs are not in a clinical setting, these are not useful letters.
Absolutely not. Letters from people who have never worked with you, who are family friends, etc. are worthless as the paper they are written on. LORs are to be from physicians who have worked with you in a clinical capacity and are not related to you.
If you are applying for a position in the US, you want letters of recommendation from a US physician because they are in a better position to assess your ability to perform well in the US medical environment. An MD in Timbuktu has no idea what the US medical system is like and what it takes to succeed here; IMHO letters from non-US physicians, especially those who have never trained or worked here, are useless and will likely be ignored.
BTW, you list yourself as a "pre-med" - this forum is for residency. Are you asking really really far in advance, did you list your status wrong, or have you posted your query in the wrong forum?