I believe you will have to have a custom face plate/surround made.

 

No you don't have to go custom- if I'm not mistaken as long as your sterio is prior to 2002 ish- a double din will fit in place without much modification. If you DO need to order the faceplate- Metra makes a dash kit for the S Type. I have an '03 S Type with a 7 inch Kenwood DNX7120, and JL Audio 12W7 with JL Audio 500/1 amp. Good luck with your mods!

 

How many hours should it take for a non-expertto replace the radio in an early S-Type with some sort of aftermarket GPS/Bluetooth/DVD/2DIN replacement ?

 

Not too long- shouldn't be longer than an hour or two as long as you have everything in hand and/or have power tools. I think it took them about an hour to an hour and a half in the shop when I got mine done, and it took them a little longer because my "03 S Type" apparently didn't run off of the same dash kit as the "03 S Type" dash kit I ordered from the UK. Mine came in as a solid grey plastic piece and my dash is black. It didn't take too much manipulation to work but IMO it didn't come out as flush as I'd hoped. I have plans to go back and get a custom faceplate made when I have free time from school.

 

Are there any web sites which show a diagram series of how to penetrate in behind the radio to remove the old, exchange the connectors and replace with the new ?
If you replace a cassette radio with something with GPS and Bluetooth and maybe even TV, you might have new connectors to route into that space for antennae and brake signal.