Is this a 2WD 205 thermostat?

Just undo the bolts, pull the lid off? will the water piss out and need fully refilling? or will just a bit come out and can be replaced by topping up the header tank? will this get any air locks in the engine or will it filter all this through?

Then I guess just take out the old, put the new one in, replace the gasket and do back up? fill with water and squeeze the inlet and outlet pipes to the rads with the cap off to bleed the system?

Thanks

Mark