I've lived in Glasgow, Scotland for the past decade, but I'm originally from the United States and was born to a Jewish mother and father (the latter converted) in Chicago.
Jewishness is as close to a "national identity" as I have. Although I became a naturalised citizen of the UK and have a strong affection for Scotland, being Jewish is my identity beyond the citizenship of any nation.
I'm not a terribly religious person, but I light the candles at Hanukah and held my first seder with my daughter this year. I hope to also celebrate Sukkot with her in the future, though that will likely mean contacting my local Reform shul, which I believe is in the nearby town of Newton Mearns.
I'm afraid I've had very little dealings with other Jews in Scotland so I cannot provide answers to the other queries. I know that we are few and dwindling due to intermarriage and assimilation with a couple of Orthodox and one Reform shul in Glasgow area and I believe a congregation in Edinburgh.