Demo data installed correctly, but there's no imges? You either forgot to import attachments when installing demo data, or your server is configured to not allow incoming attachments. You'll need to go through the theme, posts, portfolios and set featured images accordingly.
Seeing a red warning where a revolution slider should be? You just need to import the demo slider included in your themes demo data folder provided in your package.
No Menus?! Help! This is simple, go to appearance -> menus and set your registered menus to a theme location.
I'm getting 404 errors on posts & pages! Go to Settings > Permalinks and save permalinks structure.