my take on your questions
1. Can anyone estimate when I can expect my 485 to be processed?
--> Cannot predict, INS keeps changing it's pace, but be prepared for a long haul mentally atleast.
2. How long is finger print valid? (done on Nov14, 02)
--> 15 months from the date INS got it from FBI.
3. how long is medical report valid?
--> 1 year from the date you did it, but once you file your 485, (within that year), it is valid forever, unless INS has a reason to suspect that you might have a health problem.