When item with attribute bonus equipped on a character with 10 attribute levels, the item allows to overcap the attribute into 11, giving per level bonus on top of the normal 10 attribute bonus. However, this is not very noticeable on the attributes screen, as the maximum number of levels displayed per attribute is 10. To see the change it is necessary to look at the modifiers when equipping the item using the “Show Stats” button or by hovering the cursor over the attribute on the attributes screen.
The base speed is 1.4 meter plus the Combat Speed bonus. The minimum (unless other penalties) is therefore 1.5 meters (Speed 1) and you reach 2.8 meters per AP with Speed 10 ; though you can go beyond Speed 10 with items and two Backgrounds increase Combat Speed.
This speed is per AP.
Each tile/square is 1 meter by 1 meter, but the game also calculates diagonal distances. With a Combat Speed of 2, for example, 1 AP can allow moving 2 squares if in a perfect straight line.