To prevent wet-tail, feed him a bit of plain yogurt for the first few weeks.

Kaytee is a HOTLY debated topic on any animal board. They use a potentially harmful preservative, Ethoxyquin, in their foods, and their lab blocks are corn-based, which is very difficult for snimals to digest. Personally, I would steer clear of Kaytee products. Hagen is a much better choice.

I would give hi the pellets as a staple, and give him a little bit of the mix daily. (That's what I did when I had hammies)

He does not need mineral blocks or vitamins in his water.

I like to start them on fruits and veggies young, just be careful not to give him anything too watery. (Lettuce, celery, watermelon, etc)