Monitor Interval

Hi,

I set the monitor interval for my network device on 30 min., but if any port on switch or any service on server will be down I have to waiting 30 min? or this status change is send to the monitor station?

If I configure a threhold I have waiting 30 min to receive an alarm?

Another question:

.- Do I have to configure "SNMP Trap service" in opmanager server?
.- How I put in a business view several device group in the same network? Have I add one by one?
.-