Hello,
after implementing Notary services in Montenegro, all real estates related business is their responsibility now, so it is pretty safe in way that you will be registered in land registry after purchasing property, since it is their job also to apply for that. They should also be aware that you are foreigner and restrictions which you have as one.
Only thing which you need to check, or to find somebody to do it is about is land urban or not. This means at the first place, which way land is listed in General urban plan, and is it covered by detailed urban plan, and at last what they plan in it for land you are interested in.... if there is house, situation is the same, you can always build more...
Considering houses, as Tsarine already said, ask for usage or building permit, because just with this object, house or apartment is legal, all other (which is majority in NME) will be covered by legalization procedure (low is expected to be soon)and owners will need to pay all taxes for that, which is depending on zoning from 100 and more euros per square meter, probably will be possible to pay in 10 years by monthly installments.