part 1)
you are better off setting up the trigger for down device. from there, it will provide link to the devices monitoring page which would include thumbnail to the floor plan.
also when viewing a floor plan, the AP icon is red for a down AP.
part 2)
i think this is an interesting approach, can you describe more on the reasoning? this is the first request of this usage case, most HPE/Aruba customers are using AMON with light SNMP (as AMON doesn't fully replace all SNMP topics yet - but pure SNMP doesn't provide data for the newer features that are AMON only like Traffic Analysis and Clarity Live). the AMON approach removes the workload on the controller to build out an SNMP response for large topics. i'd also express some concern for maintenance when firmware updates generate new SNMP tables - as I don't often see new features broken down to the OID level in release notes.