The number of the reed depends on how soft the reed is, or in other words, lower the number easier to produce sound and the less in-tune, the higher the number, it takes more air to make a sound, but it's much more in-tune.
For people that have never used an instrument, go for a 1 and-a-half or a 2. (Rico Royal)
For people that have switched to saxophone, go for a 2 and a half. (Rico Royal)
For people with great breath support, 3. (Vandoran)
And for the professionals, 4+. (Vandoran)
If you looking to playing some jazz, use the Vandoran Java reeds.
Vandoran reeds are made and shipped from France
Each Vandoran reed comes in a package that keeps the humidity level the same.
Vandoran makes reeds for both saxophone and clarinet.
But also if you going to buy Vandoran reeds, becareful of fake products as they are imitations of high quality reeds.
Also, a good book to start on, is the "Standards of Excellence Book 1", a popular music/band book.
Most books come with a play-along CD, methods to play, and a fingering chart.
I highly recommend a private saxophone teacher, but they cost about $30-$50 for 30 or 60 minutes.
The difference between a clarinet reed and saxophone reed is that, saxophone reeds are much wider for the mouthpiece and usually cost more depending on the quality.