The immuno questions are the toughest ones on the exam by far. Try to get it down and do as many questions as you can. Concentrate on micro because it's most of the grade, but don't leave immuno to the last minute.
I remember Dr. R's questions being fair. It's tough to know what to expect because he only wrote a few for us last semester and this is the first exam for you. I would read Robbins through for each section, then study his slides like crazy. Do a bunch of questions...seems to be good for pathology. I recommend webpath (as everyone does), the Robbins review question book, pretest, and the Pathguy has a bunch of tests on his site that you can review (
www.pathguy.com).