1. If you plan on using lightmapping (which we highly recommend) and want Unity to do the Unwrapping of the objects second UV Map to do so (so you don't have to do it yourself in another application), click on the Model in the Project window. Select Model at the top of the Inspector window, and turn on Generate Lightmap UVs (towards the bottom).
This is a pretty common step to forget, so it's good to get in the habit early.