Also as a side question does anyone have any less known facts about Scottish history ?

This question cannot be answered in this sub. We only allow in-depth answers, a standard which a collection of trivia never meets.

Your question about the book is fine though.

AP Smyth: Warlords and Holy Men - Scotland AD80-1000
EJ Cowan: Alba: Celtic Scotland in the Medieval Era

I also have a number collated - although the list isn't necessarily up to date.

I'm afraid I'm drawing a blank here when it comes to comprehensive (and scholarly) monographs on the topic of Norse influence in Scotland but I can recommend some readings related to the Lordship of the Isles. Bear in mind that these are all written by academic (rather than "popular") historians and so they might not be the easiest texts to get through, but they're the only texts on the subject of which I'm aware.

Caldwell, David H. "The Scandinavian heritage of the Lordship of the Isles." In Scandinavia and Europe, 800-1350 : contact, conflict, and coexistence, eds. Jonathan Adams and Katherine Holman. 69-83. Turnhout: Brepols, 2004.

Grant, Alexander. "Scotland's 'Celtic Fringe' in the late middle ages: the Macdonald Lords of the Isles and the kingdom of Scotland." In The British Isles, 1100-1500: Comparisons, Contrasts, and Connections, ed. Sir Robert Rees Davies. 118-141. Edinburgh: Donald, 1988).

Mcleod, Wilson. "Rí Innsi Gall, Rí Fionnghall, ceannas nan Gàiddheal: sovereignty and rhetoric in the late medieval Hebrides." Cambrian Medieval Celtic Studies, 43 (2002), 25-48.

Munro, J. "The Lordship of the Isles." In The Middle Ages in the Highlands, ed. Loraine Maclean. 23-37. Inverness, 1981.

Oram, Richard D. "The Lordship of the Isles : 1336-1545." In The Argyll Book, ed. Donald Oram. 123-139. Edinburgh: Birlinn, 2004.

Oram, Richard D., ed. The Lordship of the Isles. Leiden: Brill, 2014.

If you want something more general and accessible though, then I'd highly recommend checking out BBC's A History of Scotland. Though a televised documentary, it's one of the best I've seen and will definitely provide a bit of an introduction to the topics of your query.

Oxford Illustrated History of Scotland. Not a scholar here.

• Angelo Forte, Richard Oram, and Frederik Pedersen, Viking Empires (Cambridge: Cambridge University Press, 2005).

This isn't a book I often recommend. None of these authors specializes in Viking Age history, so it's not really a good overview of the age and some literature is way out-of-date. However, the authors hail from Aberdeen and Stirling, and although this book isn't specifically about Scotland, they periodically put Scotland at the center of their story. Because it's a local interest, I think these bits were the best researched (as well as the chapters on maritime history). It should fit your needs quite nicely.

• Martin Carver, Portmahomack: Monastery of the Picts (Edinburgh: Edinburgh University Press, 2008).

This is a book I often recommend. Martin Carver is top of his field, and Portmahomack is a remarkable site. It was a monastery that nobody new about until the local church began renovations and found some amazing stone sculptures. It turns out that the Lindisfarne Gospels, one of the most spectacular books made during the early middle ages, was probably made here. Then the vikings showed up, axed three of the church leaders, forced the surviving monks to take their church apart stone by stone, burnt whatever was left standing ... and then moved in. They put a big longhouse on the site and kept the local craftsmen in business. Carver does an excellent job showing how we learned these things, what we actually know, and how it helps us better understand the very sketchy history of Viking Age Scotland.

• William F. Fitzhugh and Elisabeth Ward, eds., Vikings: The North Atlantic Saga (Smithsonian Books, 2000).

You can't ask for a better introduction to the Viking Age than this. It comes from a Smithsonian exhibition, so it's cheap, lavishly illustrated, and thoroughly researched. It gives a fairly comprehensive history of the period. Again, there's no focus specifically on Scotland (sorry!), but there's a good index, and there's chapters on vikings in Europe and viking expansion and cultural blending in Britain and Ireland. The biggest gap in this history of the Viking Age is the minimal discussion of the Baltic and Russia, but I don't think that should bother you.

• Peter Sawyer, ed., The Oxford Illustrated History of the Vikings (Oxford: Oxford University Press, 1997).

Another general survey with only passing reference to Scotland. Again, there's a good index, and the chapter that would interest you is "Ireland, Wales, Man, and the Hebrides," by Donnchadh Ó Corráin. In general, the Hebrides are better studies in the Viking Age, because they lay along the major seaways between the North Sea and the Irish Sea, so they're more integral to the "Viking" story. The rest of Scotland gets much less discussion because it can seem like a stagnant backwater compared to the bustling traffic of the Hebrides.