Like others have suggested strongly advise renting and doing some touring and fact finding .
Dumfries and Galloway has some pretty parts but stay well clear of Dumfries - run down town IMHO . Nice large villages in East/middle are Moffat Thornhill Lochmaben New Abbey there is the coast at Carsethorn and Kippford .Castle Douglas has independant shops but a bit 'mixed; in my opinion .
Kirkcudbright and Gatehouse further West might be options .The West is very pretty and coastal Whithorn etc but a bit difficult to get anywhere unless you like driving .
Access to GPs and dentists isn't good in D&G .You will need to drive and no motorways lots of pot holed rural roads. Rural roads are full of farm traffic and the A75 remember is the Euro route to Stranraer so busy . Public transport isn't great.
Lots of areas prone to flooding . Rural areas prone to power cuts in bad weather villages get cut off easily . Local regional hospital is in Dumfries but any treatment that is complex likely to be in a city hospital so another consideration if getting older.
Property tends to have oil heating or Macgas (bottles) also septic tanks are usual. Its not uncommon in the rural areas to have half million pound houses next to a rented farm cottage .Rural region so lots of farm traffic and farm animals can be suprisingly noisy .No street lights in a lot of hamlets/villages .
Shopping limited lots of 'Tesco towns ' and eating out not much variety -again you'll likely have to drive to access a decent eatery .
Culturally its a bit varied the Wigtown is the book town and Spring Fling festival is worth a look .
Relatives lived and worked in region for many years but retired to Yorkshire - horses for courses I guess - I used to holiday with them in D & G as a child and later with my own young family .Went back recently with my now grown up daughter and found a lot of changes nice for a holiday but wouldn't want to live there .