Hi Nz/jen
I saw your email making enquiries about your husband's family in Caithness and I noticed that your John Mowat was the son of Donald Mowat and Elizabeth Sutherland. I have a Donald Mowat and Elizabeth Sutherland in my maternal tree (Mowats) who came from Brabster, near Canisbay. They had nine of a family and John Mowat was the 5th child of that family. Donald Mowat and Elizabeth Sutherland would have been my gggg grandparents (would have to check on that) but when I saw your relatives with the same names I wondered if they were the same people. I am descended from their eldest son, William. If you would like to give me your email address I could send you a copy of what I have of that family if you are interested.
Also regarding Alexander Mowat born 1813 it is possible that your friend could be related. They had big families in those days and there would be lots of Mowat cousins at that time.
Regarding gravestones you could make inquiries (via email) to the Wick Council who would manage the Wick Cemetery but there are other cemeteries on line in Canisbay, Corsback and others which I can't remember at this moment. If you just fed in 'Canisbay Cemetery or Gravestones' on line I am sure that would suffice.
I see you are in NZ too.
Good luck.
Elise Linney