Hi SF,

1. This can be done by engaging scene lighting from within the Interactive Render Settings (the dialog box that opens when you click the "up" arrow at the top of the Assembly Room window.)

2. It's really variable from scene to scene - just like normal 3D lighting; It just takes some experimentation. 

3. That's because of the transparency maps. Check out this thread.

4. Bump strength almost always needs to be adjusted to accommodate changes in lighting and closeness of the camera. As a rule for  humans, the bump maps seem to work best at between 3 and 6 percent. 

5. C8's big improvements are going to 64 bit, improving large file handling. There are other improvements for lighting and a nice boost in render speed; especially if you have 64 bit box. But if those areas aren't immediately important, C7 will still treat you well.