in CQ/AEM pages are resources, which have a resource type. Based on this resourcetype the correct rendering logic (in many cases a JSP) is called to render this resource. So you never call a JSP directly.
To 1: You could implement a servlet filter, which checks for the "under review" conditions and then does a redirect to your "under review" page.
To 2: As said, you cannot address JSPs directly. Create pages in /content, which have the proper resource type. And then put your JSPs below /apps. Basically create dedicated templates and components for this case.
Jörg