It's the <title> that's important, if that's not right then you can forget the others. Don't worry about <meta> until your <title> is right.
You've optimised your page for K1 K2 K3, and you're ranking well for K1 K2 K3. This is what you want, isn't it?
If you want to rank for K2 K3 then IMHO you need to do this on a different page - the presence of K1 gets in the way.
I don't really understand this. If you have unique content relating to K2 K3 then this is a non-issue.
Forget tags and titles, it's the content that makes the difference. Do you actually have unique content relating to K2 K3 city1 compared with K2 K3 city2? If not, IMHO it's time to put your creative hat on and come up with some unique content :-)