I think it's easy to see why the 12.11. or 10.11. would be a little beside the point, isn't it?
As for the origins: since medieval times the eleven is the fool's number, so the time with most elevens is the time to start carneval. You'll find the number repeated in the institutions of the carneval as the Elferrat.
In my opinion, it's also a fitting date to have ended this utterly senseless war.
"Bureacracy: I know it's a cliche, but standing for four hours in line at the Bürgeramt!? To be registered by the police for no reason (no need to in the UK, so why here?!) Pain in the arse. Sicherheit, Sicherheit über alles."
The main reason for registering: taxes. If the UK had continued with the poll tax, there would have been a need for registering to make it work.
By the way, the little joke at the end of this comment would be considered as extremely rude by most Germans.
I think that there is a misunderstanding of the law. I don't think that it applies to foreign partners of German citizens. If they're married, they have the right to come to Germany. A similar situation applies to EU citizens with foreign partners: the partners have the right to stay in the EU, and this trumps German law. (As for the question what's special about EU citizens: there exist limitations in regard to the nw member states for another few years, but otherwise an EU citizen has the right to live and work in any other member state. A totally different legal situation than non-EU citizens.)
The law applies to non-EU citizens with the right to live in Germany. Their direct family members can move to Germany, too. I think that rationale for limiting this is the fear of Turkish men looking for wifes in Turkey with a more traditional understanding of gender roles who stay mainly within the Turkish sub-culture you describe and end up having little interaction with the world outside the families of their husbands. The law requires them to take German lessons within three months of moving to Germany or they loose their right to stay in Germany. Personally I can't judge how common this is but I can understand the rationale of the German state wanting these wives to get knowledge in German which allows them to act more independently within German society (i.e. not needing their husband to translate for them).