Delaware Guy,
I know it's your first trip and you don't know what to expect but it's fairly easy. Why bother with Orbit? Making reservations, having to prepay, is it worth the trouble? You won't need any help going through customs, just make sure you bring a pen on the plane to fill out the immigration and customs forms you'll receive after you take off.
At SJO, as soon as you clear customs, walk outside and make a left. You'll see a small booth. Just walk up and pay $12-14 (not sure the going rate
) and tell them where you want to go. You may even be approached by a driver who will escort you to the booth. You will be on your way in under 5 minutes. Do not go off with an unlicensed cabby who wants to give you a ride without going to the booth. They know most hotels, but the SL is one they have trouble with. They don't know it by name, so I usually just tell them "mi hotel es dos cientos metros oeste del hospital calderon guardia" (my hotel is 200 meters west of the Calderon Guardia Hospital). That's their "address". You can download a map of the SL here: http://www.sportsmenscr.com/SM%20Images/map.jpg (but their site is down for now) and show it to the driver.
It's very easy, any specific questions, post here or PM directly. I'll be happy to help.