Armstrong isnt bad. Do you own a sax already? If not I suggest going to
http://www.saxophone.com and getting one there.
Also what sax do you plan on playing? Soprano, Alto, Tenor, or Bari?
The main thing to remember when switching from guitar, is that your key is going to be different. Soprano and Tenor are in the key of Bb, so when your playing a C scale it sounds like a Bb scale on Piano and on Guitar or any other insturment written in the key of C. Alto and Bari are in the key of Eb, so a C scale on Alto and Bari will sound like an Eb scale on C insturments.
Vintage Saxes, you can get one off ebay. I woulden't suggest one for a beginner though, becuase they have their own little quirks, and a lot of time require lots of work.
Yes your reed needs to be moist. It won't play well unless you do. I've been playing for about 8 years now. So you can trust what I say.
I'd also suggest looking into lessons. They will help a lot.
Now while Ska music isnt all too complicated, it will proboboly take some time.