Hi Jester,
Welcome the the club, its normally the norm to post an intro in the new members section just to let us know a bit about yourself so we can get to know you (we like making new freinds)
As for the oil and price, this sounds like a typical main dealer price so dont worry about that. next time buy a service manual and do it your self (its very easy) and you can save money on labour etc.
Now for the Oil, 4.0L would be the amount of oil needed for just an oil change, 4.5L will be the amount needed for an oil AND oil filter change the filter will soak up a sertain amount of oil (like chucking a spounge in the sink) so they have done the correct thing