A set of very specific questions

Depends on what you use DSP for. What it shows in the DSP panel.

But as a first approximation, you don’t lose anything serious. Roon was a great product before DSP was added, we all lived happily.

One guess: if your DSP is set to do serious upsampling, it would increase the demands on WiFi. Upsampling in Roon is a luxury, not necessary,