Ok, if it were me, I would steer you toward the Pioneer systems. They have been doing the Nav all in one stuff longer then anyone else and their products have always been rock solid. Another reason is that on the underside of the N2 (IIRC) there is a little switch under a "Warranty Void if broken" seal that will allow you to by pass the "no video while drive" feature. Kenwood makes good stuff too and you would not go wrong with them either.
I bereave that if you want BT that Pioneer has an adaptor out that will add it. On the size question it should be roughly about 7 1/2 deep, about 4 tall and about 7 wide. Basically if you measure the height of a single din and double is, depth and width are about the same.
On the chimes, yeah, it was me. I know the set up you read about and I DO NOT recommend you do it. First, the harness you will need is a GM-22, basically it is a bundle of wires about an 1 1/2" in diameter that is about
20' long and requires you to keep your factory radio in the vehicle. I have seen a few setups like this and the end result was problem after problem. Plus, once you take the factory radio out, you will see you have limited wire run area, so installing ALL that wire is a PIA.The reason he "had" to install both the Pioneer and the factory radio is because either the shop that did the work didn't have a flipping clue as to what they were doing or he bought the stuff with out doing a little research.
Where are you located, if you were in S.E Arizona, I would offer to install this stuff for you. I could knock out the basic installation in about 2 hours, this includes the GPS pack, the tuner, antenna, wires et all for a fair price.