how to show tooltip for parameter values in ssrs 2012?
how to show hardcoded message in parameter area in ssrs 2012?
You can't (not without making serious changes to your environment). The Parameter area is pretty generic without many options. If you can't configure it through the GUI - it's likely no possible or not worth the effort. That's been my experience.
SSRS does not provide great tools for creating the optimal user experience. For what you want to do you would create a asp.net front-end that talks to SSRS or directly to the database.
-- Itzik Ben-Gan 2001