Immigration aspects of Schengen? Not sure what you mean as Schengen is open borders in Europe.
Once any other European county grants citizenship to someone then they have access to live in Britain - via a passport.
Just because we have border controls doesn't affect what other EU countries do as regards their immigration policy- ultimately if those people decide Britain is the place for them once they are deemed German citizen, then their policies are affecting us.
Most of the cologne attackers are of North Africam origin - fact, not right wing propaganda. Why are there all these Morrocan and Algerians in Sweden and Germany currently seeking asylum? The crisis response you referred to? What Moroccan crisis?
Mismanagement isn't excused because there is a crisis I'm afraid.
Merkel said survival of the fittest - if you can get here you're in. Merkel created a free for all where no one has any idea who has arrived what with being able to say 'papers are lost, honest I'm Shrian'. Fact again, not right wing propaganda.
Native Arab speakers are required to try to pick out genuine refugees.
Why would anyone tie themselves to such incompetent leadership. So yes Merkel has made this a relevant issue for the EU referendum.
Leave voters had decided prior to these events that our final autonomy will be voted away if we stay. Undecideds are seeing it in action now, maybe they hadn't understood impact of being tied 'ever closer'.
Our votes will shape our children's and grandchildren's future - so you really want them looking back saying in 2016 we gave Europe the right to say 'your country voted to be part of EU so time to STFU'' and tow the line '?
I'm sure they'd say it more politely, but that would be be jist.