1. Yes. Full backwards compatibility with hardcopy retail games and controllers, aside from Gamecube controllers.
2. On the Wii U, they are lacking (with the exception of the eventual release of Monolith Software's X). The Wii recently had a trio of great JRPGs, though: The Last Story, Pandora's Tower, and Xenoblade Chronicles. I think the Wii is an all right console for JRPGs, especially with Xenoblade.
3. No. As is the case with Nintendo's eShop of the past, they seldom have digital sales, and when they do the sales are so marginal that it rarely matters. This is especially true for first-party games. Third-party games are cheaper elsewhere, for sure.
Currently playing: Rhythm Thief and the Emperor's Treasure - Let's Play on my YouTube! :D My Gaming YouTube: http://www.youtube.com/user/MasterChief3624