From what I found on the net, it appears that the iPad 2 (seems to be the cheapest...) has no GPS localization, except for the 3G version. Is that right ?
Yes, but this is true for all iPads. You need to purchase the 3G version if you want GPS. But you don't need GPS for the Jeppesen plates if you want to save money.
What kind of iPad do you use ?
Myself, I use an iPad 2 (3G), at my company we have the latest models (lost count about the number). There is no significant difference, the "retina display" makes the charts a bit prettier to look at, but the iPad 2 is good enough to produce a readable display.
Do any of you use or heard about using an Android powered tablett (such as the samsung Galaxy Tab) ? If yes, are the Jeppesen apps (Jepp View, Flight Deck) compatible ?
AFAIK there are is no Jepp View for Android tablets yet.