Hi,
By clicking on the Options button you will be able to set your Default Units (Inches, Centimetres, Millimetres, Inches, Pixels), you can Enable the snapping to other elements, you can enable rotation snapping, you can set Touchpad Devices...etc. If you need to resize your image you can use Alt + Z.
Also, you can give us an example of what exactly you want to set in the program and we will help you.