I need to change radiator hoses

I need to change radiator hoses. I need to drain and refill the coolant system. To drain do I need to do anything other than drain the radiator/ isn’t there coolant in the engine block/ do I need to drain that too to change the bottom hose. If so, how do I drain the coolant in the block?

Also, when I refill, is there something I need to do to get air out of the system. I read something online about air can cause a problem with the G-05 coolant.