Nagios Support Forum

I'll bet there is...
https://www.nagios.org/ncpa/help/2.0/active.html

Enterprise features are usually features in the UI, not related to monitoring. Monitoring is checking status of things on hosts in the network. Since you have XI you might ask nagios if you can temporarily downgrade a nagios host to play with it and see what features aren't there. Or create a VM ins...

This depends on the plugin defined in the command. Nagios sets status based on the return value of a check.

Yes, nagios can check exchange,

Restart ES and check it's status.

I guess this is where you read the output and resolve the issues.
Asking others to read for you seems strange.

Not as far as I know. Nagios reacts to state changes. The text output is meaningless to nagios. If you want it to your plugin needs to react to different text output.

Looks like an argument to check_log or the defined command is not right. Run check_log directly from the host and get the args right.

Nagios can monitor an exchange box just fine. Just because a host is running echchange doesn't make it much different than any other host.

How do you know the trap gets to the trap interface?
Check for the trap in the snmptrapd.log and snmptt logs.
What do you see?