You would get a better response if you posted in the Tube Fishing forum above this one.
I'd get breathable waders and use appropriate layer underneath. You may be able to get away with hip waders too. If you don't plan on using oars, then you'll need to get flippers. However, looking at the size of that I would use oars.
Fish finder is a nice luxury item as most kayakers use them.
You do not need to register unless you plan on putting a trolling motor on the back (it looks like it has a mount).