Maximum Number of Zones

[dan]

Not an answer to your last question but a compromise on the issue of a power-off button.
I whipped up a shutdown_button plugin that provides a button for stopping SIP.

If you really want a button to stop the software you will need to install the plugin and access the button through the PLUGINS menu.

Dan

P.S.
If you are not connecting the top ground rail to the bottom one you will need to figure out a way to connect the ground connections of the shift registers to the top ground rail.