If using a distributed virtual switch, I understand the VM should stay connected during a vMotion (unless you are vMotioning to a host which is not configured for the same dVS)
Regarding Collector trace level - this is only for our own internal logging, and should only be changed if advised by our Support.
If you wish to modify the visible alerts in SCOM - you can use standard SCOM overrides for our rules and monitors. For example, just right-click the Alert, and go to Overrides... and choose - disable, override, override for a group, etc.
You can also find all nworks rules and monitors in Authoring section of SCOM console - just clear any Scope and search for 'nworks'