Well what part are you talking about? Most likely removing a fan blade from an shaft isn't a good idea unless its made to come off. Will have a key way with a set screw.

Probably not. There has to be more then just a tight fit between the blade & the shaft, some sort of mechanical locking device.

They are a "press-fit", tapped on with a hammer at the factory. If you really need to remove it, I would get the hub really warm with a heat gun, then wearing a glove try to pull it off the shaft. Less likely to snap if the plastic is a little soft.

What type of equipment are you asking about?