Re: steering wheel grease
If you mean the steering tube (in front of the outboard), that's about the only place on a boat where you could put anything (marine grease, white lithium, engine oil, etc.), but it's hard to reach past the few first inches. Some swear by the Steersman nut; haven't tried it myself but I don't boat in salwater, so regular (once a year) oiling is doing fine.
As for the cables themselves, they can't be greased or oiled. Why did you say that "it seems a little dry"? Is is hard to steer? Could be the pivot pin/tube on the mid-section of the engine...