Those plugs have been in there for a very long time and may tend to seize upon removal. I would just crack them loose a very small amount and then spray PB Blaster so that it can soak down thru the threads overnight. They won't do this at a shop and if the threads are damaged, they will charge you big time.
Read the instructions, some of the new plugs have a plating and you are not to use an anti-sieze compound. Again, a shop may not follow these directions.
The plug wires are easily damaged, just figure on replacing them.
