I'm a pretty hairy guy. What do the ladies prefer in terms of grooming? Is that an appropriate question to ask the provider?

You might find your answer there, or on their website.  From what I have read, many if not most, prefer either trimmed or shaved privates, no flossing wanted.  Can't say I blame them.

I've also had providers tell me they don't care at all if you have your hair and even that it's more manly.

Trimming is obviously a good idea, but try explaining to the spouse why you're now shaving that area and you've never shaved it before.  The "sports injury" excuse won't cut it for the area you need to be shaving and trimming.

Oh wait, no survey done.  Maybe one should do one.  Now, my serious response, I believe this has been discussed in the general discussion board and it seems to me the majority of providers expressed the desire of some kind of manscaping.
Either closely trimmed or shaved.  The reasoning seemed mostly so they didn't floss, better hygiene, or texture.

How frequently do people in this hobby encounter pubic lice?  Would manscaping have a prophylactic effect, so to speak?

Hobbying a very long time, never got lice.
 

Pubic lice are so rare amongst people who wash properly.  We sometimes see them on mentally ill streetwalkers and drug addicts.  I doubt that more than a small handful of people using this board have ever had them

but it was back in the early 80's, way before either men or women did much grooming down there.

and yes, crabs were quite common back then, they weren't confined to streetwalkers and drug addicts, mentally ill or otherwise. I am guessing you are under forty five and weren't sexually active in the 70's-80's.

Yes, sexually active, been hobbying since the mid 70's.  Even then didn't see many street walkers.