Dov good to see you are still around.
Tires, there's quite a few choices these days. Pick your poison, Bridgestones RE71-RS, Yokohama A052, Falken RT-660, Nankang CR-1 (or CR-S I think is the latest rendition), or Kumho V730's, just to name a few. I believe Nexen also has a competitive tire out but don't know anyone local that has tried them yet.
The Miata question I can't answer, but maybe Mr. King or one of the many resident Miata experts can chime in?