In Superman: The Animated Series he was also vulnerable to electricity when he was fighting Livewire. He ended up coating himself in rubber or something as an insulator so he could fight her.

Mostly, Superman seems to be vulnerable to whatever the plot calls for. wink

As for Force attacks, Superman is vulnerable to magic, but I've seen him be resistant to psychic attacks, so you could make a sound argument either way. I see the Force more as a psychic thing than as a magical thing, though, so I think he would be vulnerable but not as much as a normal person. As Ben says, "The Force can have a strong influence on the weak-minded," and Superman has a strong enough will to wield a Green Lantern ring.

From The Green Lantern Corps Wepbage :
Quote
Will power can also be added by another strong will joining with the ring wielder. On two separate occasions, Superman joined wills with the Green Lantern Corps of Earth and a pair of Green Lanterns, Hal Jordan and Guy Gardner. [Action Comics #589, Adventures of Superman #473]

"It is a remarkable dichotomy. In many ways, Clark is the most human of us all. Then...he shoots fire from the skies, and it is difficult not to think of him as a god. And how fortunate we all are that it does not occur to him." -Batman (in Superman/Batman #3 by Jeph Loeb)