1: Potato drops aren't increased when harvested with a tool that has fortune on it, regardless of the fortune tier (the results using no enchant, fortune I, II, and III are all the same)

2: I was expecting that, given how carrots ARE affected by Fortune, and noticeably so, potatoes would be as well.

3: I ran several full 8x8 fields, splitting each into 32 plants with each tool, each time. I ran each set of 32 plants three times with each tool (four diamond axes, one unenchanted, one with fortune I, one with fortune II, and one with fortune III), but for each one, the average yield was ~81 potatoes, regardless of the enchantment. By comparison, carrots through the same test yielded ~81 for the unenchanted axe, ~101 for fortune I, ~118 for fortune II, and ~136 for fortune III. I don't know whether these two crops acting differently towards fortune is intentional or not, but I couldn't find anything mentioning it clearly either. I did, however, try the same world with both 1.4.2 and 1.4.3pre, and got the same results for both.