Great post Sid! I enjoyed it and I own a tint shop.

Most of the customers don't even ask about the brand of the film we use. They just want it dark. So we actually ask what they want and also tell them about clear tint which blocks the heat w/o the dark tint.
I don't suggest expensive film at all. There are very good inexpensive films which will look just as good and last just as long so I steer them away unless they absolutely want it. The brands we carry are Suntek, Solar Gard, Madico, Llumar. Most popular being Suntek, which is on my 07 Fit. Because it's economical and has manufacture's lifetime warranty. Make sure your installer use the film he said he will use, because it's very easy to say one thing and do the other. I have known some installers to actually admit to buying films from Walmart and believe me you don't want those.
We do computer cut our films and so we do get some people buying that locally, but I usually see them coming back for additional cut because they messed up. I don't recommend doing it yourself, unless you will be doing lot more cars. You need to buy different equipments and it's for sure you will make mistakes. There are lot of installation videos in Youtube which can be helpful. With right equipment and patience it could work out.
If you need to remove old tint, just get a steamer and slowly peel it off. That's what we do. With the heat and moisture, old adhesives loosen up.
If you do buy precut tints, just know that they aren't heat shrunken. I couldn't belive some ebayers stating that they are heat shrunked. In order to properly shrink the film, it needs to be put on the window of the vehicle being tinted because what shrinking does is shaping the tint according to the window curvature. So unless they have same vehicle to shrink on no way and they have cut for all the cars...
For the beginner, shrinking can be the most difficult part. It is very easy to crease the film while removing the fingers on the film as heat is applied.
Hope this will help. I didn't think I'd write this much.