What Pentax bodies work with K mount lenses? Short answer: all of them!
I suggest you download the PDF users manual for any body you are considering and check that for specifics. The
K-5IIs manual has an appendix showing what functions are usable with what lenses and any caveats. If you have specific lenses you want to use and there is no specific caveat in the manual saying you cannot use it then it will work.
Sorry I can't help on question #2. You can run a dealer search from the Pentax website. And I'm sure you can call Pentax directly to help find a dealer.