For someone seeking a general introduction to both languages, I think you cover just about everything. I was unaware that Irish had once been written with both grave and acute accent marks (i.e., the fada in Irish or "s(t)ràc" in Sc. Gaelic).
I recently saw a post on Facebook by a fluent Scottish Gaelic speaker in Scotland in which he referred to Scottish Gaelic as "Scottish." I've heard a few other people, including an Irish speaker, use this term, but I have my doubts about whether it will catch on...
There used to be a fascinating video on Youtube of an hourlong lecture by Brían Mac Lochlainn on the connections between Scottish Gaelic and the Irish of Rathlin Island and the Glens of Antrim. Sadly, it seems to have disappeared. In the video, he talked of teaching Irish in Belfast in the '70s and being introduced to a student's grandmother from Rathlin. She told him that in the old days on the island, they frequently had contact with visitors from Islay and Kintyre whose Gaelic they could understand easily, but that they once met a fisherman from Donegal and "we couldn't understand his Gaelic at all."
While Donegal Irish is in many respects the closest surviving relative in Ireland to Scottish Gaelic, it also has a number of significant differences that are not found in Gaelic at all. At one time, there would likely have been a "dialect continuum" in which each dialect would flow into the other. The strong similarities of Islay, Kintyre, and Arran Gaelic to Irish (e.g., phrases like "gu robh math agad" or " 's math leam" rather than the standard "tapadh leat" and " 's 'toil leam") would seem to confirm this. Unfortunately, Gaelic has completely died on Arran, is in terminal decline in Kintyre, and is severely threatened on Islay. Most younger speakers there speak it as a second language and their dialect doesn't tend to be very local.
An interesting variation on the dialect continuum hypothesis was related to me by my friend Brían Ó hAirt. He talked about how when he first met Scottish Gaelic speakers from Lewis, the cadence of their speech was strongly evocative of the Irish he learned in Conamara. He said that he had found some scholarly backing for this in an article by Mícheal Ó Siadhail where he suggested that prior to the decline of Irish, dialects may have existed in broad "rings." This might explain why some features of Conamara and Munster Irish also have some parallels in Gaelic.