1. how long does it take your system to boot from cold start till you see win main screen ?
I'll answer this first question then defer the rest for a few weeks.
From the time that I push the ON button to getting a windows 10 desktop is in the vicinity of 14 seconds with what will probably be my most common set up although just playing around with various configurations I've gotten as low as 7 second boot times. Main reasons for the rapid boots are the ASROCK motherboard which has a setting that gives it a post time of around 3 seconds. Turning off the fast boot mode on the MB pushes the overall boot time up to around 30 seconds. I'm booting from Western Digital BLACK SN850 NVME Generation 4 2TB M.2 SSD drives which are crazy fast.
For now, I'm still using my Focusrite as the primary sound and a Tascam conroller surface although I'm contemplating the purchase of one or two Steven Slate Audio RAVEN MTi2 Multi-Touch Production Consoles if I can deterine that they are compatible with the rest of my system.
I'm setting this up as a triple boot system with one drive booting up to a dedicated gaming PC, one for video rendering, and the third for all audio functions. Since I'm having to go through all of my programs and plugins on my old PC so I can deactivate them and transfer them to the new, I've not yet done a lot of audio testing on the new rig, still using the old until I'm sure I can make a relatively smooth transition to the new system. I did some experimenting on the old machine simpling cloning the hard drive and using it in the same machine and it knocked out a number of things on the cloned drive including BIAB, Addictive Drums, Vegas, and Sound Forge all of which seemed to think they were on different computers rather than just cloned versions of the same drive.
I'm setting a deadline for myself of labor day to have the audio stuff transfered so I'll try to have some more answers for you then on how it is performing.