If you have an open ruleset for reports to be created in, the Express report viewer will have a Save As option. This will create a new report definition from the report you have loaded.
Guardrail warnings are intentionally not displayed in Express. The Express portal is designed to create all the rules that make up the application in a manner that conforms to bets practices and not introducing any guardrail warnings. As Express doe snot expose all of the capabilities of designer studio, not all guardrail warnings could be addressed within Express. It is the intention of the design that all guardrail issues are addressed by appropriate resources using designer studio.
With 7.3 I am not seeing any issues with the action menu or the items in the actions menu. If you can provide some more information about the scenario in which you are seeing this issue, we can look to provide you with more information.