Grossly oversimplified but on a macro level it’s basically right. Wealth and power concentrated in the hands of people whose only goal to increase their wealth and power at the expense of each other. Ideas of prestige and imperial ambition and nationalism and revanchism are the puppet show they play for the masses while the ones in charge hope to make money.

I don't really think they could have, in the grand scale of historical inevitability. Within a few centuries, united Germany and modernised Russia would have been as issue for them, and at that point it's just an issue of sheer demographics. They didn't have an open frontier to expand into, and instead would have to rely on conquest of their direct neighbours, which isn't really terribly effective. And their position in the Baltic means they couldn't really have leveraged their naval strength into a colonial empire since a single blockade of the straits between Denmark and Sweden would have completely dismembered them.

As it says in the article, he was arrested because he was a supporter of the disgraced Duke of Suffolk.

During the reign of Henry VI, the Duke of Suffolk was largely in charge for a bit. Under his leadership, the Kingdom of England lost most of its land in northern France. This was a time in history when such failure would be dealt with in a way that we would consider harsh. Suffolk was accused of treason and arrested and then murdered.

Baron Saye was arrested and executed in the same kind of factional purge, being a supporter of Suffolk.