A Ph.D. is nice, but not really valuable, if it's a Finnish Ph.D. and you want to come to the US. If that's your plan, it's FAR better to get your current M.D. and then take the Ph.D. in the US -- which will take AT LEAST 3 yrs.
Thing is, that you'd have a hard time matching in ANY residency, with the poss. exception of IM and FP, without US clinical and/or research exposure. And I doubt your non-US Ph.D. will be very helpful. It'll look nice on a cv, but once the PD sees that it's a non-US degree it WILL be fully or at least partially discounted.
Taking derm as an example you'd need to look at:
1. Will you with reasonable confidence be able to get a residency in Derm at a top program in your home country? If not, it's highly unlikely that you'll succeed getting one, at any program, in the US, because of the vast applicant pool.
2. Since grades and the structure of your MD program will be meaningless to the PD, you will need to AT LEAST match, and more likely exceed, in the directly comparable stats with other applicants, i.e. USMLE, publications and the like.
3. You will inherently be a lesser known entity than an AMG, which will be a real problem if the applicant pool consists of supremely competitive AMG's. Only way around that is to work in the US - probably in research or clinical research - so you can get great Letters of Recommendation from well-respected leaders in the field, or possibly work with someone who knows derm PD's.
4. You will be locked out of some programs, because they will not sponsor a visa for you. If you do get a visa, it's most likely a J-1, which will take you back to your home country for a minimum of two years after completing your residency. So working hours and salaries as a newly minted board certified US physician wouldn't be really meaningful to you. To add insult to injury, you can in no way be certain that your US training will be accepted in Europe. I personally know people who trained at top institutions in the US, only to do the whole thing over again when they went back to Europe.
The above would obviously also apply for the other fields you mentioned.
I don't want to rain on your parade, but matching into a competitive field as a FMG is exceedingly difficult, and would require a vast amount of hard work and luck... And a Ph.D. wouldn't give much of a boost, except if it's a US Ph.D. The one other thing which can set you apart, is if you do all or most of the training in your preferred specialty in Europe. You'd probably still have to redo the whole thing in the US, but it can set you apart from other applicants.
Don't get me wrong. It is of course possible. But last stats I saw (a couple of years ago) I think it was 3 FMG's among 226 derm residents. Stats a bit better in othopods and ENT, but not much.
BTW: Getting an MD in the US isn't a option for most Europeans, since you'd need a US undergrad degree, or at least US premed courses, to even apply. I have firsthand knowledge of a person from Singapore who applied for a Ivy League MSTP program with a PERFECT MCAT score of 45 and tons of research, who was rejected by the MD adcom because they didn't think he had enough EC's, US shadowing etc.