No, that is not possible. There is no way as yet to get MC to do averages in the files view.
The only place where its done is if you have a view scheme and display as thumbnails in the files view. Then when you mouse over the thumbnail it will show, amonst others what the avg value of the track ratings is.
I've been asking to have this for a long time so in the meantime i just created a custom field called Album Score and put these values in manually. Its possible then to create a calculated field which combines [Album Score] wth [Album] and then use that field in a viewscheme to show both on the same line.
Otherwise if you have the skills, you can export out a listing of your files in MPL, create some scripts in a language of your choice to work on them and then re-import the MPL back into MC. I think this will be the best way to do any arithmetic manipulations as nothing stops you from using the most fancy formulas in your script. See mark_h's posts in this
thread if you are interested. Be careful with this method tho as it has the potential to mess up your MC library!
At the moment there is no way to assign a different colour to text in any of the views. Funnily enough your idea of red, green, etc is something i asked for but using custom art to indicate it in a files view. That request is still outstanding