Yes, please add a list of hard and soft caps to the front page, it'd be awesome to have a reference for those.
Q: How does dodge work?
A: Dodge works with diminishing returns. As an example, let's say you have 10% dodge in your runes.
You grab Ninja Tabi, which gives 11% dodge.
11% dodge +
(89 * .1) = 8.9% dodge
For a total of 19.9% dodge. (Note that the 89 comes from the percent remaining from the previous dodge percentages have been calculated.)
It looks like dodge is calculated backwards, i.e. you're getting full value from the last item purchased, and purchasing a new item nerfs your previous boosts/items. So in the initial example buying the ninja tabi nerfs your rune page to 8.9% instead of 10%.
That begs the question if the same is true of masteries and rune pages. Does a dodge buff from masteries nerf the dodge buff from rune pages?