I'll be of no help to you regarding the iPod questions.....
However, on the Kestrel
, my recommendation would be to buy the Kestrel that meets all the input requirements of your ballistic software, nothing more and nothing less.
I use Patagonia Loadbase 3.0 Mobile on a Dell Axim X3, and the Kestrel 3500NV answers all the questions posed by that program.
Now if only I could shoot as good as the software ballistic solution