Re: spark plug replacement
Yep remove the engine top cover. This will be either plastic of aluminium depending on the age of the car.
You will then see the 4 coil packs. These also need to be removed and are attached to a rail held in by 3 small allen key bolts. No need to remove the coil packs individually , take the whole lot off on the rail.
BUT before you can remove it you must pull the 4 plug leads for the small plugs. These will more than likely be stuck very tight but try to avoid pulling them too hard and definitely dont try to lever them off eith anything because they are easily damaged. Rotating them to and fro will loosen them.
I'd say remove the engine cover the day before and spray some WD40 down the plug holes. Will make it alot easier to get the leads out.