It seems to be 10mm , had noise after replacing hubs so was going to clean things up and put this to proper torque , but not sure where to find this information without knowing the nomenclature for these parts

Also do i need to loosen loosen and tighten them in criss cross order?

 

The Haynes manual lists the hub to knuckle bolt torque as 63 ft-lbs. I would tighten them easily in a couple of stages.