For issue #1, I can't reproduce it showing up correctly in either RTP or the regular 3D preview, in RTP it's black, in regular preview it's pink for some reason (probably outscaled texture?). Anyway, switching the Image Map Shader to use Object UV instead of Plan Y fixes it. Also note that you do not *need* to use a Default Shader, you can plug the Image Map Shader in directly, unless you need some features of the Default Shader.
Issue #2 is just an example of a limitation with the current material previews, basically. There is no workaround that I'm aware of except to temporarily change the Projection to e.g. Through Camera, which will allow the texture display correctly, but then won't work for rendering. It's a known limitation and certainly should be improved at some point.
- Oshyan