Well in the first scenario you need a resident to make it work so that the patient is still being taken care of. It is pretty much the extreme of bad medical education, but I see it happen...
Rehab-related issues are the bread and butter of PM&R. Hospitalist don't get trained in rehab, thats why it takes a specialist.
The main rehab units are TBI, stroke, SCI, general, oncology. Patient's are technically supposed to be 'medically stable' to go to an IPR unit so they don't need daily insulin adjustments or BP medication adjustments, IVF's, lines and drips, etc. We generally utilize the ED for medical emergencies that come up.
Brain injury/stroke: How do you treat a disorders-of-conciousness patient versus a higher rancho level. How do you get brain injury patients on the road to being awake and recovery. We deal with medications (neurostimulants, mood stabilizers), spasticity management, procedures (TDCS, botox, joint injections), agitation management, paroxysmal sympathetic hyperactivity, hypercalcemia, chronic respiratory failure, disordered sleep/wake cycles, depression, pain, dysphagia, aphasia, etc etc.
SCI: same thing: spasticity management, bowel/bladder management, neuropathic pain, chronic pain issues, power WC equipment, AD, may get a vent patient etc.
general rehab: mostly poly-trauma, joint replacement, amputation, debility, transplant recipient patients. Acute on chronic pain is mostly what we treat here.
oncology: sees a lot of brain injury and SCI patients from cancer.