[3rd party patching failing frequently (SMScriptException (3): Error in script.)]

Yes, I also frequently see these same errors across multiple sites and organizations.

[Enable Maintenance Mode on offline devices]

Currently we can only place a device into 'Maintenance mode' if it is online. Devices which are offline do not have the command option to do so. 

Every other RMM I've used has this capability. A workaround would be to create a separate group with its own policies and then move the offline device into there, but that is convoluted and not ideal.