Engine Code P261B Water Pump

Apologies. I love my car, but that doesn't mean I know a heck of a lot about them, in general. I put in my car's information on the dealership sites (and it seems to be all of them, I didn't try just one) and ask for water pumps and they give me listings for at least a dozen things, with all kinds of diagrams and blow ups and related parts. Then they call it the water pump assembly, and with things like gaskets for it and other bits, and mounting stuff and so on ... as a noob to their website, it's very confusing, and I don't know if that water pump assembly has all the parts I need to replace the pump, or if I have to get the gasket and/or other things separately.

That's why I asked. But it had the proper part number, so I finally decided it was probably the whole thing. (Though, yes, will also be getting thermostat, since it's cheap and right there, and the actual Toyota coolant.)