When you first install the shaders mod it can take around 10mins for the mission to load...you need to be really patient here. Reinstall after each update...pretty easy.
I prefer just a window rather than full screen. That way I can browse the internet etc while missions load and check manuals etc
In game resolution is irrelevant for VR.
ASW has no performance impact...it smooths out frames but does introduce some minor artifacts. Some people prefer to not use it for this reason but you get stuttering if your not hitting 90fps.
I have same setup as you and have been flying VR since it first release. I'd recommend some Pixel density and also some cockpit shadows...visually this makes a big difference.
At the end of the day, it's a tradeoff between performance and visuals...only you can make that decision depending on what you prefer.