Whatever you get, make sure it has anchor holes in the skirt. My buddy has a Clam and it doesn't have them. Kind of sucked in the wind even though we banked it.
Use a drill and anchor attachment as mentioned. Frustrating, especially in the cold, to try and get them started by hand.
When in doubt, anchor guy lines on the hubs facing into the wind. Sucks to have a hub "pop in" when you aren't expecting it, especially if close to the heater or you're fighting a fish.
You want insulated for sure.
Get a fan to push hot air down.
Don't get bigger than what you're going to use it for.
Use foam floor mats, at least under your feet. Makes a huge difference.
GET A ZIPPERED BAG (if it doesn't come with one). My biggest frustration was trying to stuff it back in a bag that only had an opening in one end. I have the Eskimo 949i and bought a bag for a different Eskimo that has a zipper instead. Frustrations disappeared.
The new hub accessoried (shelves, rod holders, etc.) are nice but not a requirement.
Lots of options for lighting - search around and get creative