Dashboard pages stores only last 24 hours data.
Older data: If the store data is active for the relevant metrics, you can find it on the “Reports> Metric Reports” page.
Thanks for this wonderfull question !
Unlimited custom actions can be added on "Configuration > User Defined Metric Actions” page.
Here is a tutorial about adding custom actions for your reference: http://www.wlsdm.com/tutorials/advanced-weblogic-monitoring-develop-jmx-mbeans-and-automate-with-wlsdm-metric-actions.php