Do Cadillacs have 1 DIN or 2 DIN slots for head units? I found a head unit I really like and looks like it will fit but it is for 2 DIN slots only. From my understanding only some imports have 2 DIN slots.

Some cadillacs do have double-din head units (mine does). If I remember correctly, so does yours.

Single din is 2x7 in size, double din is 4x7 in size.. If you want a single din radio, you can get mounting kits and have a plate or cubbyhole fill the void.

I'd also recommend a wiring harness so you could always convert back to the old setup, say, if you were to sell the vehicle or wanted to rip out the stereo after an accident (for insurance)

Not sure if it's a domestic or import thing, but a vehcile with some space in that area will get a double din assigned to it, helps the designer widdle away some space

Yes! If mine has a double DIN I am getting that head unit with my next commission check! That would be great. This is what I'm looking at. (http://www.crutchfield.com/S-MxUw3kLzzNT/cgi-bin/ProdView.asp?s=0&c=17&g=168550&I=113DDX7015&o=p&a=0&cc=01&avf=N&search=) The reason I am going with that one is because I want an in dash monitor for that "stock look" and any other HU with a monitor that folds out is not only tacky IMO but also causes a conflict for me. In my Fleetwood the climat controls are right above the HU area, if I had a retractable monitor when it would be out I couldnt adjust the climate controls which would cause a problem for me. It's HD Radio ready, TV ready, Navigation ready, and had DVD build right in.

Great choice! Somebody here brought that same unit to my attention, I realized how much improvement kenwood has made with their excelon series. The DCA is a 24 bit one, ther same in my nakamichi!
Congratulations, I'm sure you'll enjoy it. Don't forget to post pictures of if when installed, huh?