Re: How many types of surfaces have you actually played on?
In the US, the huge majority of hard courts are Deco-Turf, or a similar concrete-like surface, so I've played a lot on that in parks and against other schools.
I, however, have played most of my life on green clay, Har-Tru, courts, as that's what we had at my school, my club, and most places I went on vacation. Because of this, it is definitely my favorite surface and the one that I'm most comfortable on. It's worth noting that indoor and outdoor green clay actually play somewhat differently.
I have also had the opportunity to play on red clay, grass, indoor hard, Rebound Ace (just once), and that awful synthetic grass stuff that they like to play on in Japan. The one surface I really want to try is carpet, but hardly anywhere in the US has it.
Oh, and during the Sniper attacks in DC, our high school coach would set up a "tennis court" in our gym, which consisted of two trashcans with an extension cord in between them dividing a sleek hardwood floor...