Oh wow, what an interesting thread!
I just caught up - it's a bit much this early in the morning 
I am German, lived in England for 6 months, then moved to Scotland some 20+ years ago. I was delighted that I was allowed to vote in the Ref as I see Scotland as my adopted country even though I don't identify as 'Scottish' or 'British'.
My family still state that 'PD lives in England', meaning Britain. They give me an indulgent smile and pat my head in a loving manner when I correct them.
DH is Scottish - he is not particularly outwardly nationalistic (and voted No), but is a very proud Scot and struggles to maintain his equilibrium when repeated labelled 'English' - interesting visits at my folks at times…
Wrt to federalism: Germany has been a federal republic since WW2. The 'Länder' have devolved powers with the overall 'umbrella' of national powers in Berlin. Every 'Land' has a 'capital' city with a city council (to govern city issues) and regional council which governs issues for the 'Land'. The Bundestag in Berlin is the 3rd tier if you want. It seems to work, there are elections more frequently than here and turn-out tends to be 60+% which is not great, but okish.
I think one important difference is that there are many Länder and nobody perceives themselves as a different nation - we are all German (well, maybe the Bavarians are more German than the rest of us
).
The whole country is less 'Capital city centric' than the UK - yes, there are urban centres of increased affluence and population density, but Munich is as important as Hamburg as Berlin as Düsseldorf etc. in many respects.
Also the phrase 'the eyes of the world are on us' which I have heard and seen as headlines: erm, well, really only a little. I know the Basques and other nations keen on independence have been acutely aware what's been going on, but generally? No, the world has not been holding its breath.
I was in Germany last weekend (just before the Ref) and I was asked once or twice which way I thought it was going to go, but nobody was particularly aerated about it - whatever the outcome.
Immigration: this country needs immigrants. The population is getting older (I work in the NHS as see daily evidence of this), we are having less children (on average) and many Brits (I'd include other 'rich' Western Europeans) are not prepared to do low-skilled jobs at minimal wage - not a very nice statement to make, but an unpalatable truth IMO. We need people to come in and remove rubbish, work in caring jobs, sweeps the streets and provides the backbone of our economy.
Yes, I appreciate this is a terrible and gross generalisation.
I was shocked how quickly AS resigned - I did think his position had become a bit untenable and his life's goal had not been achieved, but I did expect him to stick around to help clear up the mess tbh. Nicola is a force to be reckoned with, so we shall see.