I don't like events for these things, seem to me a workaround and can be gameplay-breaking (what if you are playing as Pomerania?).2.0 Changing the de jure borders of the German kingdom is hard, but in my personal version I added an event for the transition of the Pommeranian duchies.
It is definitely easier, but given that we have Bavaria and the rest, it would be nice to use them right? So if we really want the unified German kingdom, we can write a decision to make it out of Bavaria, Alamannia, Saxony and/or whatever.2.a Here I disagree, I prefer the larger German kingdom, maybe split in a Eastern Frankish kingdom of German and a Middle Frankish kingdom of Lotharingia.
Didn't know that, sources? I thought the Imperial Eagle is by necessity double-headed and the one used in Vanilla for the kingdom of Germany (single-headed) is kind of fiction based on the Sicilian one (historically introduced by the Hohenstaufens) with a different background to make it look 'modern'.2.b-1 I totally agree regarding the colors of duchies.
2.b-2 The German Eagle predates the Hohenstaufen dukes and so the Swabian CoA uses the German colors and not the other way around. This also implies that the Hohenstaufen Sicilian Eagle arms are derived from the German Royal arms.
We can debate the details.2.c Being independent or the emperor would be a good condition, especially regarding the large German kingdom.
An exception would be Bohemia, but instead (maybe as an OR condition) of having the Bohemian culture I usually use the condition of being duke of Bohemia and duke (actually margrave) of Moravia.
In my own version Frisia is titular, and I use similar conditions for Frisia as for Bohemia.
Lotharingia is larger, which makes it harder to create, but also makes more like Burgundy and Italy. Creating such kingdoms, should either be done by the emperor or an independent ruler.
I don't like titular titles for the same very reason Paradox doesn't (they can be problematic gameplay-wise).2.d In my version that would mean uniting Germany and Lotharingia; de facto making Lotharingia titular, something IMHO should eventually happen anyway.
You see, by yourself you are placing the 'kingship of the Romans' on a different level, see my second post above.Regarding the German kingdom (Germany with Lotharingia), I beg to differ, it did exist as a part of the empire; or to put it differently it was the kingdom in the empire, not requiring a different entity in the empire like Italy and Burgundy.
This will always be debatable.2.* Regarding the provinces, some decisions are debatable. IMHO Sankt Gallen and Chur (as parts of Raetia) are better of in Swabia, I'd keep Salzburg in Bavaria and Württemberg in Swabia; and finally Steiermark, which is rather tricky, I like a duchy of Styria, but that's too small for the vanilla map, in 1066 Steiermark should be in Carinthia, until 1180, and after 1192 the duchy of Styria was united with the duchy of Austria, so keeping it with Austria IMHO makes more sense.