Question Button interaction area does not match (possibly related to canvas/camera?)

I'm still fighting with the 2D camera, it just doesn't show what I want it to show.

Now, to add insult to injury, as I was trying the different canvas/camera modes I think I might have done something like scale the Canvas (which is somehow tied to the camera?) or something similar and I've ended up with a user interface that doesn't match the graphics (see screenshot: when you mouseover a button, it lights up, I scribbled in the areas where the buttons _actually_ light up)



I selected the elements in the scene and their bounding boxes look normal, any sort of scale value is set to 1.

I set up the entire UI with the canvas in World Space, but now if I set it to either Screen Space mode it distorts the canvas to a really strange dimension and then the camera is locked in a super zoomed in setting.



So two questions really:
1) What's going on with the interaction space on the buttons?
2) (regarding the second screenshot) how to I make my camera match my canvas? (I tried every camera option, the only one that does anything at all is the "size" field and only in with the canvas World Space)

 

Well, I'm saying UI, but it's a 2D game.