Ed,

Glad to hear that the gliding/soaring bug may have bit you.

Regarding #2 - Can Gliders take off and land at any airport/airfield...or are there known designated airports?

Lets break down this question into the ups and downs of it.

Landing - Legally, as Cindy said, you can land any aircraft (which includes gliders) at any airport. Practically speaking small grass and local hard surface low-traffic airports are "easy", mid-size airports you should be on the radio first (if you are able), and finally larger airports with commercial traffic you might/will cause quite a hubbub. But, when in a jam, you gotta' do what you gotta' do. It can be better to just land in a farmer's plowed field adjacent to an active airport than to land on the airport itself (while steering clear of pastures and rocky areas). "Landing out" is something you will need to learn about and prepare for in any case. ;-)

Takeoffs - This is trickier. Glider (non-self launch) operations are considered SLOW by the powered airplane world due to the need to position the glider and tow plane on the runway, hooking up the tow rope, taking up slack, and then launching. Many airport managers (paid, unpaid and/or self-appointed) are very friendly to glider operations while a (thankfully) few are downright hostile. All the glider operations shown on the SSA.org web site have already crossed this negotiation bridge and are actively working to stay on the good side of the local "authorities". Some lucky clubs even own their own airports which avoids nearly all of these problems in the first place!

Bottom line: Begin with an established club or commercial operation as the best way to learn the ropes and stay safe. http://www.ssa.org/WhereToFly

Best of luck,
John OHM Ω