1. I'm not interested in getting NVME at this time because I won't be utilizing the speeds available on them.
This part I'd focus on. While you don't need the speeds, the 660p is cheaper, would perform a little better than the Crucial drive, and wouldn't need to worry about the extra cabling, helping the aesthetics side of thigs.
Not a big deal, and I wouldn't advocate spending
more on one... but for your needs, I don't see any reason not to.
My budget is ~$2000 just for parts so I'm okay for now.
At $2k, you should still be able to achieve what you want - but might benefit from allocating some more of the budget towards a better GPU. Hard to say though, as the see noticeable gains over an XT, you do have to spend a good amount more.
How do you think this build would be able to handle Ultra Wide 1440p, 144 hz monitor say at high?
I'm not too familiar with most of the titles you listed, but I do know Monster Hunter World was fairly unoptimized for a long time. Not sure if that's still the card? 1440p, maxed out needed a 1080TI to drive 60FPS at one point. Not sure about now.
As for 1440p 21:9.... it would handle it, but I suspect 144FPS in the titles you play (assuming they support it) might be a bit of a stretch at "high:"