When you select an item, you can resize it by dragging the notches on sides and corners, or you can type the size in pixels for width and height in the right panel. 

When the chain icon between size values is active (blue), width-height ratio will remain the same. 

When you select an item, you can change its position by dragging the selected item or you can type the position in pixels for x and y values in the right panel. 

You can adjust the opacity using the opacity slider under Format tab.

You can adjust the border radius using the Radius slider under Format tab.