yea while it is off you shood do it, incase u find somethign later on and need to take em off again, coz that would just be a pain in the arse to do it twice
shoudl only cost about 30 or 40 a head. i don't think you would need to do it as it isn't an aloy head. but it couldn't do any hard.. getting them crack tests would be the go i spose.. while they are off ya might aswell do other stuff to them too..