That's right out of the comics, although they do tend to overplay it in the films. I assume electricity has always been one of his weapons because electricity itself is one of the most powerful natural forces and controlling it is one of science's greatest achievements, so it fits with a character that's part scientist, part sorcerer.
My understanding of his control of electricity has to do with his armor, not as a power. He's a sorcerer but also a crazy mad scientist. I mean that they keep giving him electric powers & not a suit that controls electricity. Granted, I may be wrong that it's like 90% suit for his power over electricity, but I was pretty sure that was the case.
Yea, it's the suit in the comics and he has no powers apart from sorcery. Most authors and artists don't even show him using sorcery, but sometimes they do. All of the modern incarnations show him as gaining powers along with the FF starting with Ultimate FF and including both films.
Not sure when the sorcery elements started because I so rarely see him using them. Was he a sorcerer in any of the Lee/Kirby stories? I don't remember any where he was. I do remember him using tons of gadgets he invented though...I thought that Lee wanted him to be a pure mad inventor.