I'm so glad to hear that your fps rates are locked in. Maybe all your computer needed was that update and restart. But you'll know if you ever have high rates again—the surest signs of an overworked graphics card are the excessive heat and the fan revving up to compensate.
I've never used Windowed Borderless myself, so I'm not familiar with the screen options, but I think the point of it is that it takes up the entire screen while giving you the benefits of playing in windowed mode. You can certainly move the window; the manual says you need to specify X and Y coordinates for the window:
https://westechsolutions.net/sites/WindowedBorderlessGaming/manual#Settingawindowsposition
Otherwise, you could ask around here for help from people who do use the feature. (There are at least a few.)
Anyway, it's great that you got (almost) everything working to your liking, and I hope you enjoy playing on your new system.