pull them out & put them in a vice with a socket inside, clamp closed the vice & oil will leak out. you will need 2 do this quite a few times but it works,just dont be 2 heavy handed as you will crush them.
The answer depends on how you maintain the vehicles. I currently own one with 185K miles, aside from the slave cylinder going out (parts cost $20.00), I have not had any major problems with it....
Remove the two bolts holding the thermostat housing cap (which is connected to the hose coming from the top of the radiator), then just pull out the old thermostat and replace it with the new one.