DLC here is a thread you might find interesting with some good websites to visit:
http://forums.studentdoctor.net/showthread.php?t=101626
Programs do things differently. Path is split up into Anatomic path and Clinical path. You can do a residency in either one or both. Most people aside from people on a definite research and academic track do the combined residency. Individually, each is a 3 year program. Together, it is a 4 year program (clearly because 3+3=4, in case you were wondering). The required curriculum includes 18 months of AP (usually about 10 months surgical pathology, 4 months autopsy, 2-3 cytology, 1-2 dermpath, neuropath, renal path, etc) and 18 months of CP (Clinical chem, micro, immunology, blood bank/transfusion, hematology, informatics, etc etc etc). The remaining 12 months are elective time. (These # of months vary) Many people also do fellowships (sometimes at the same institution, sometimes at others) after the four years. Commonly this is surg path, cyto, some clin path field. Some will do multiple fellowships (i.e. surg path followed by GI path). But you can be board certified and be out in practice in general after 4 years.
Some programs start all residents on AP for one year (or even two years). Others will integrate CP and AP from the start. Where I am some of the residents have started on autopsy, some surg path, some like me on clinical. During some of the clinical months, again this depends on your program, you may have some level of contact with clinicians and patient wards (well, you're always going to have contact with clinicians, but you get my point). Blood banking sometimes requires visiting patients. Micro sometimes requires daily conferences in which you discuss specimens with medicine house staff, Cytology may require you to do FNAs.
You're right there is no transitional or prelim year. July 1 of PGY-1 you start with pathology. You don't have to worry about garbage like inserting IVs, writing discharge paperwork, admissions orders, etc although there are some tasks on clinical path months that have parts of these normal house staff activities included. Again, this varies based on the program you are at.
Most programs save most of your elective time until your 3rd or 4th year when you have a better idea on where you want your career to be going. There are also generally daily lectures or seminars on topics appropriate to the area you are in, and often weekly conferences for all the residents on things like interesting surg path slides, autopsy conferences, etc.
There is a lot of misinformation out there as to what pathologists and pathology residents do. I wouldn't trust much of what other med students you talk to (unless they are interested in path, in which case they may know what they are talking about) or what a lot of attendings from other specialties say. Who knows where a lot of the info comes from. Go talk to a pathologist if you have specific questions, I am sure your school has some people who would love to talk to someone who is interested and provide you with advice, programs to look at, etc.
Always good to see soon-to-be graduates interested in the best field in medicine!