Once again, Shaun - I sincerely appreciate your input. I've tried looking through census docs, and have located John in 1881 and 1901 in Edinburgh, with his siblings Anna (1876 - in Malta) and Mary (1878) - but I believe he married Annie (Murphy) in 1910, and I can't locate any 1911 info. It's possible he married in Ireland, because Annie was from Ireland, possibly Antrim area and may have been born in 1879. I seem to recall being told that John was born in Ireland too (his father was stationed there for a while), but without any documentation, I'm shooting in the dark.
I'm sure John Campbell was a piper though, and I remember him telling my brother he'd make a good piper because he had good teeth..haha. He was wounded also (thankfully, because so many pipers were killed), so the information you provided fits well. Looks like I was correct on the regiment - but had the battalion wrong. The puzzle is coming together.
I owe you a debt of gratitude.
Jim