Sigh* Carlissa, you give my inner nerd a boner.
I believe that one of the Spartans was referenced as a Spartan 3, however the lore in my mind started blocking that part out along my second play through.
I believe the Chief would be about 45-50 at this point. He was selected at Seven and was almost done most of the training before the Human Covenant war started. Spartans were originally made to take on Colonial Insurgencies. The war lasted 30 years, and Chief was on Ice when it ended.
The Pillar of Autumn is the horse that the Spartans were suppose to ride in on. Its an older, but beefy ship. It was crash landed on 04 in the first game.
I AM THE WIKI! <.<