In most cases, yes it can. Any of my artwork can be scaled up or down (to a point.) Just remember that - for example - if the image you like is shown as a rectangle, it will scale up or down as a rectangle. If the image you like is shown as square, it will remain square.
Yes! They are intended to be used. You won't scratch the image, as it's showing through from back-to-front. The boards are also heat safe and may be used as a trivet.
Depends on the order. Most things I can have completed and ready to ship within a couple of days. Custom ordered extra large metal prints can take a little longer.