You measure the linear footage of the fascia board runs around your home and divide by 5′, the length of each Rainhandler section. If you end up with a fraction, round off to the next 5′ increment.
Yes, it can be cut. Cut it with the hacksaw or aviation snips.
For unprotected doorways, the Rainhandler Doorbrella accessory ensures that water is directed to the Rainhandler sections on either side. The Roof Valley Rain Diverter may be needed at the bottom of long valleys with exposed metal flashing.
Because of the standing seams, the Doorbrella must be mounted another way. Using a 5″ Drip Edge Extender and mounting the Doorbrella on the top of it solves the problem.
Some metal and barrel tile roofs tend to shoot water further out the harder it rains. However, Rainhandlers have been successfully installed on hundreds of homes with metal roofs. The simplest thing is to try one or two sections. If there problems we can give you advice on the accessories needed to correct them. Then you can proceed with the full installation.