seeing that I am playing a bit of this, keen to get some pointers, please..German bow..so not worried about French hold... Specifically, to allow the bow to decay on down strokes especially, and to let the sound be smaller, not forcing the tone, even in forte? More bow speed, less pressure/weight? Space between notes in intervals of a third and larger? “brushed,” not staccato, sostenuto, or excessively spiccato? unless intentional? Regards to all
None of the above, necessarily. Or at least all the time. It's a big topic, especially when discussing early music on modern instruments. My best advice is to read books on Baroque performance, and find and read treatises from the period. There are no absolutes, just as there are none in modern performance.
I’m certainly no baroque expert, but I think you’re coming at this from the wrong direction. The technical questions will make more sense from a more musically informed position. Listen to recordings and watch videos of period performances, like Freiburg Baroque Orchestra or Age of Enlightenment. Try to get your hands on a bass with gut strings and a period bow just to see how it feels. A lot of strokes and sounds will happen automatically. You can read treatises as well, if you like. The early music scene is generally more academic and informed than most. Research is a big part of the culture.
Research is indeed part of the HIP scene, but beware even that. Entire trends have developed out of one interpretation of one part of one treatise. As Paul says, listen to the music and you'll soon find the people that have really thought it out.