Questions about Sauron
 

What exactly is Sauron? Is he a man? beast? or what?

For questions such as this one only needs to ask TheGreatElvenWarrior.

Sauron is a Maia (a kind of lesser angelic being, the greater being the Ainur), this information can be found in The Silmarillion.

Nerwen the nitpicker strikes again!
 

Not quite.

The Ainur are the entire race of angelic spirits.

The lesser ones are indeed the Maiar, but the greater are the Valar.

Just so you know, the singular forms are Ainu, Vala and Maia– in each case you add -r to make the plural.

Ah yes, quite right. Slight error, thanks for the correction! I haven’t read The Silmarillion for a while, guess I should read it again.:D