Hot Tub on a high Deck

(Colorado)

I am wanting to put a hot tub on a second story deck above the 1st story deck. The height above ground is approximately 12 feet. The hot tub manufacture says it is 6,000 pounds with people in it. The deck size will be 13 feet long and 11 feet out from the house on a ledger. The holes drilled are 5 feet 8 inches apart and 18 inches wide for the posts.

Questions I have are as follow

1. Can I just pour the concrete in these posts drilled that are 18 inches wide and 4 feet deep without having to put a square footer in the bottom?

2. I am going to put a glulam in for the beam that is 12 inches high and the 13 feet long of the deck. Will this be enough support with 2x12 joist on 16 inch on centers. I don't mind doing 8 inch on center if that will help.

3. My post size are 6x8 will this support the hot tub?

4. For the beam for the first deck do I put the posts on top of this beam or just run it from the concrete all the way through?