Metro inconsistencies

On Start, if the mouse pointer reaches the edge of the screen, and there are more tiles to see, the screen scrolls - I don't have to use the scrollbar at the bottom. Everywhere else, it seems necessary to use the scrollbar at the bottom to see more screen, at least with a mouse cursor - is it like that with tablets?

If I have a bunch of tiles, that could form a nice neat rectangle, the rule seems to be that it won't.

The easiest way to scroll with a mouse is to use the wheel anything else is hit and miss.