What is the actual speed cap for Kaisers?

This is my scenario.
Empress weapon normal 6
Booster -2(?)
Speed increase inner ability -1
Kaiser gauge thing (I forget what it's called) -1 (i believe it was as i recall that it doesn't stack to give -2)
Kaiser's Majesty -1
Green Potion -1

This would bring a normal weapon from normal 6 to speed 0.
Now if I were to use a fast weapon, such as a Stonetooth, would that drop to -1? Or is there a hard cap of 0?

One more thing. The increase atk speed buff in dojo, would it stack in the above scenario?

It would increase to faster (-1) with the Stonetooth Sword.

The Dojo buff already breaks the speed cap, so it would stack on with the rest to become faster (-2).

Dojo lets you get to speed 1. Green pot just disregards any sort of cap there might have been.