looks like you have a lot of plans.
for the power converter, you are looking a the wrong type-- the one in the link is to allow 12 volt electronics to work on a 24 volt auto electrical system- 99% of all cars on the road today use 12 volt electrical systems.
for the sony radio, i would recommend taking a trip to the local electronics store that has one and try playing with it, and make sure that it has all the features you want, and are easy to access. as long as it meets your requirements, it is perfect for you.
i am not a big sony fan(i have one of their sub amps), i really don't think that any of their car audio stuff is amazing, or headturning, or revolutionary anymore(the pentagonal subs were a new take on the sub shape game), but it just works, and as long as you are happy with it, it will be perfect.
otherwise, check out the ADV. FAQ link at the top middle of the info bar for a lot of info on connections and hookup, and general advice on carputers.