What hardware and software solutions work and what are the tradeoffs for connecting an Arduino Due to the internet? I gather the ethernet hardware is much cheaper than WiFi hardware (€29 versus €69). In either case (wired or wireless), what software stacks and drivers work under AtmelStudio?
Well, your best bet is to import the arduino libraries in your Atmel Studio project. Then you'll be able to use existing code to connect to the "traditional" Ethernet Shield using SPI.