When kerning type the keyboard shortcut adjusts spacing by +/-20 units. It doesn't specify what units but I'm guessing it's points? The other fields are in points, but the kerning and leading fields don't specify.
Doesn't really matter.
What I'd like to do is be able to adjust that amount, change the increment to say 5 units for finer control. I'm starting to design more and more on photoshop. I would love to be able to set type quickly, instead of entering values manually. It would be very useful to be able to set the kerning, tracking, and leading increments like those apps allow us to.