1)
Ok, D-STAR (Digital Smart Technolgies for Amateur Radio) is mature, sophisticated and fun. If you have been skeptical or took a look a few years ago as I did, it's gotten way better. It's not Plug n Play. And you'd be bored with it if it were. That said, D-STAR is a hybrid mode RF with full world wide, IP connectivity. It is not the future it is the present. And vital to understand and become operationally comfortable with. Jump in or be left behind.
Since no single site/link is comprehensive to learn about this mode. Here's one way to delve into it.
1) Icom owns the commercial space. Get familiar with their offerings
2) See this excellent siteD-STAR Info.COM
3) Watch the 3 Hour 2012 Dayton Excellent D-Star Introduction with John WB4QDX
4) Buy the very smart primer Nifty E-Z Guide to D-STAR Operation
5) Cruise the D-STAR Users. ORG site
6) Yes see the DVAP PC Dongle for an IP Portal. This is a must.
7) Last but not least. Go to the RT Systems Web site and become familiar with their product. It's probably a must buy.
Then you can start on Raspberry Pi
The ID-51 D-STAR HT (if that is the path you choose) is a feature rich radio, preloaded with reepaters around the world. Memory Management of this tool is critical to making it rock. Call Sign routing, GPS linking, Reflector connectivity all are enhanced with software.
There's all kinds of stuff to learn and enthusiastic users. I just got in during the past 10 days and I'm having a blast.You will too!