No, our notifications system has nothing in common with Jira/JSM notifications. You can use Raley and Jira/JSM notifications at the same time without conflicting.
Raley does not switch off or modify in any way existing Jira Notification Schemes or JSM Customer notifications
Yes, check out this article for more details
Each notification configuration might return an error generated at runtime. Examples of this errors are:
These errors are reported to user on the list of Raley notifications just below the names of respective notification configuration. When you fix it, assuming that the fix was correct, the error message will disappear next time the notification configuration is successfully run.