"selskap" means "company" (as in a firm, companionship, or a party). "bedrift" means "enterprise" or "undertaking" (in both sense of the words).
So they can be used to refer to the same thing, or something different.
I'm guessing not. In my dictionary all the references to 'lage' + (something) for example: lage mat, lage bråk, lage mål etc. all involve an individual or group of people doing the action. In comparison, a company is a legal entity but not a living one.
From my dictionary and the sentence here I think that 'lage' is used when living entities make something, but not otherwise.
Of course, I could be totally wrong.
Could this sentence be translated as "The company is operating at a profit", or does one need the continuous tense for that?
As I understand it there isn't a continuous tense distinct from the present tense in Norwegian.