Do you have any recommendations for a good SLR brand?
Canon or Nikon is industry standard.
I'm also an amateur/sometimes pro photographer ("I'm a visual person!"), and I use a professional setup: Canon 5D Mark II body, with quality "glass": 24-70mm f/2.8L, 50mm f/1.4, 85mm f/1.2L II (portrait lens), and a macro at 100mm f/2.8, with an all-purpose 580ex II flash. I do not use dSLR for derm photos: I have a tiny TINY pocket Sony Cybershot...surprise surprise! These photos won't be used for publication anyway, just for my own edification. Anyway almost all programs have a great dSLR for publication-quality photos. You don't need a dSLR.
One program I rotated through had TWO Nikon dSLRs with sick awesome macro lens and macro flash...$$$$$$.... The residents were very good with the camera.
My mentor, a private practitioner, has an awesome Visia photo machine (from Canfield), which can document progress over time utilizing the same angles and lighting. I plan to have one in my office one day.