I spent 400 hours shadowing an Internalist this summer. None of this is expert opinion but is all right as far as I have seen/heard/read.
Internalists are employed generally in three different ways. One is as a Doctor with a private practice who sees patients on a long-term basis. Most IMs with a private practice then go and see patients, usually their own, that are in the hospital.
Second are internalists employed by hospitals which as you said are hospitalists. They are assigned to patients for the duration of their stay and are in charge of their general care and coordinating between specialists who are also seeing the patient.
Thirdly are IMs that work in Clinics. These are more similar to EM in that they see a patient they've usually never seen before and treat them once, either dealing with the problem or referring them to other doctors or sometimes the ER. Obviously though you see less severe cases than ER and more migraines and back aches.
Internists do average around 200k, give or take. That is second lowest (above PEDS) for doctor specialties. I will say though that if you are going into medicine for the money you are going to regret your career choice. The IM I shadowed had plenty of money because he never had time to spend it, hahah.
And that leads into your final question on hours. IMs have VERY heavy hours, probably as heavy as any specialty of doctor. The IM I shadowed would work in his office from 8am to 6pm, then go see patients at the hospital from 6:15 to 8-9. He did that five days a week, was on call all night once every eight days, and usually spent his entire Saturday doing paperwork/dictation/etc. In short, IMs are one of the busiest and paid one of the least. All that busyness being said, he did have a family who he did get time to interact with, but certainly not as much time as something like dermatology or most other professions.
Now don't get me wrong, for all the bleakness I just wrote my 400 hours with him confirmed beyond a shadow of a doubt that I want to be an Internalist. Internalists are never bored, and there is less of a chance for monotony, in my opinion, since you see cases of all types. He also got to do A LOT of diagnosing since he was almost always the first person the patient came to with the problem. Sure, about 30% of his patients each day were, "You're still overweight, exercise more and here's your diabetes medicine." but each person did have some little nuance or exception to keep it fresh.
It is also a very fulfilling work, since most of the patients he saw he had being seeing for the past 15+ years, and he really had formed a personal attachment with them. Also, IM is the most needed specialty (since no one wants to do it) so there can be a great sense of satisfaction from filling the most needed role in a community. And if Obamacare stands firm through whatever happens this November and we get 30 million more people on health insurance, IMs are going to be desired even more than they are now, if that is even possible.
Hope I helped.