Colour choice is a bit tricky as well (why can't anything be easy). Amongst the 4 CS colours I like the Vista Blue the best. The issue here is that at least on the updated Ford website, in Canada it only comes with the parchment top. I would rather have black plus you cannot get the parchment top in cloth which I think I would want. I had black twice before and although I like it I would not do black. Never had white before; fairly cool to this but think I would like it with the parchemnt/black interior and parchement top but again no cloth top in that case. Leaves Red Fire I guess which in pictures at least looks a little to pink for my liking. If I had to choose a CS it would be Red Fire with the black cloth top and parchment black interior with the black dash trim.
I agree on fabric seats fading quicker than leather but I have never been a huge fan of leather (have had before) and somewhat don't like the thought of getting back into the car after having the top down on a hot day and searing legs etc. I do love the two tone CS leather choices though. Much better than single colour leather thats for sure.
For regular GT colours I would like to have the guts to do grabber orange but am not sure I do. Would likely go Tungstun Grey
With work and family life being so crazy right now I don't think I can get this done by Thursday. This would effectively be a third, summer only fun car and I am grappling with how wise this would be as well. I have trouble buying anything that is not a neccessity and this is definetely not that.
How is insurance on the Stang?
Color is very much a personal choice of course. The GT/CS is a third vehicle for two of us also, so is not always driven daily or in bad weather and will not be winter driven. All 4 colors are good in the CS I think, and the Vista Blue would be good choice. Lots of buyers on several Mustang forums I scan are getting the VBlue. In fact, the GT Vert I had on order was to be VB so I obviously like it. I recently saw a set of pictures of new Performance White GT/CS Vert with the black cloth top and it was much nicer than I expected the white to be. Redfire is a touch too ordinary for me, but it is popular. Also, I think the Tungsten Gray is gone for 2007 in the regular GT colors and the new gray is called Alloy Gray. The Grabber Orange would FOR SURE command attention!! Maybe too much attention, and I would be too chicken to order it, as you said.
As I am in BC and deal with ICBC, insurance is not much different on the car than it is on either of our other 2 vehicles. If you are under a private insurance scheme, the Mustang "may" be more pricey, but you could shop around in advance.
As to not buying things that are not a necessity - well. very personal again but in my case, I am over 60 yrs old, and had a couple of med issues so feel like I want to do/experience some "extras" while I can. It is unlkey that the purchase of any Mustang GT is a "necessity" for anyone as there would always be a cheaper/more practical/boring alternative. Only you can make the call.

The cloth top is only available in black, as you say, all Parchment tops will be vinyl. I have seen pictures of the VB with Parchment top and that would not be my choice but some like it a lot. I think the VB is best with the black top (cloth or vinyl) and the black/dove interior seats. I am really not a fan of the Parchment top at all, and I have seen pix of the white CS with Parch top and it's another non-starter for me. The IUP pkg dash strip can be satin alum or charcoal and, again, it's personal taste. Mine is satin but the charcoal looks just as good.