I was just recently looking into this for my own home and gathered information. It so happened that the company installing this film on Long Island is in the same building as my daughter's office, so I stopped in and asked all kinds of questions. Very interesting answers.
Here's a link to the company I'm talking about. Maybe it answers more of your questions; if not, why not call?
MetroSolar | 3M Prestige Clear Window Tinting Films Dealer/Installer | NYC | Long Island | CT
I'm saving up for new windows (21!), and am looking into the various possibilities re UV rays, etc.
Good luck!