Yep, that's correct. The Seed is the DSP. All of the other products have a Seed plugged into them, they're basically just interfaces.
I'm on a Windows PC. Doing all of the development in C++, no graphical tools. Compiling / flashing via the command line.
Eventually I want to get everything set up in Visual Studio, but for now it's working just fine.
You can apparently use PureData and Max/Msp, but I've vowed not to touch anything graphical this time around...
I already had a fair amount of experience with C++ so take this with a grain of salt, but I'd highly recommend attempting to learn to write code. You'll have a much better understanding of what's going on, and I suspect there will be more peer support going in that direction as well.