Oliver, you've received enough instructions on renewing your engine's spark plugs to fill a book.
One mention as to gap, it was referred as 32mm, that's not quite right, it is 0.032 inches.
as for type of spark plugs, use the plain jane copper cored plugs, they say they perform the best in our Benz engines, they do for me anyway. But I have the Jacob's Omni Magnum Ignition System.
A hint in removing and installing the plugs. Have two types of spark plug sockets at hand. One plain deep socket and one with the rubber insert for holding the plug in the socket.
When removing the spark plug from the cylinder head use the socket with the rubber insert. This socket will bring the loosened plug out of the bore.
When installing the new plug use the plain socket and when torqued properly this socket will come free of the plug whereas the other socket many times stays with the plug and the extention comes free of the socket.
Remember to appy anti-seize compound on the threads and silicon lubricant on the rubber insulator.
Now you can write two books.
Happy Trails Pip Pip from the Midlands, Houston!!!
Donald, El Cheapo