What we are concerned about it that you have "ganged" 4 outlets into 1 supply with no overload protection. In the case of a 4 outlet powerboard it has a 10amp circuit breaker built in, that little black button on the side. In your case your building the 4 outlet power board, but you have not added any form of overload protection to it.
The extra 4th outlet is not the problem, even back with just 2 outlets
here I mentioned
"Have you considered circuit breakers, just if your splitting 1 x 10amp supply into 2 x 10amp outlets, it may be easy to forget and plug elements into the both of the outlets."
I understand you have no intention of running the second element and the drill at the same time. One day you may decide to do a brew and throw that second element in the pot to bring it up to strike temps quicker. Not thinking about it, next thing you've fired up the mill and milling away with a load total load 2400w element + 800w drill + laptop (maybe even the pump to help with a nice even water temp) , all running through cables and switches designed for 10amp, with no overload protection. I would hate for a fire to break out and you loose loved ones over it. If you had the 10amp circuit breaker in place, in theory it should trip and save you.
Think of each 10amp outlet being a potential of a 10amp load. Never leave it up to the user to always make the best decision.
With the NC circuit you would not have power for the laptop. I planned it that way as your element would be the full 10amp load. As Glen W mentioned, really you should have option 1 or 2 and also possibly add option 3 as well.
I am not an electrician and your electrician will be able to advise best on this subject.
QldKev