In regards to RGB I noticed your cpu cooler is the stock amd cooler. The stock cooler can definitely run a 5600 but if you want to add rgb something like a thermaltake peerless assassin can add that while also making your system cooler and quieter. Just depends how much its worth to you.
Do you have a microcenter near you?
Newegg has been caught doing some awful stuff, in particular they try to sell not just used parts, but defective parts as new to GamersNexus. This is particularly awful given their horrible return policies.
That said there are many things with low return rates I do not mind buying from them. I would steer clear of monitors and mobos personally since they are by far the items I am most likely to return as defective.
The board you have chosen can NOT fit two of the m2 nvme ssds you chose. You could opt for a traditional ssd plugged into one of the sata ports.
Regarding rgb your case has a big ole see through side panel so at this point it would be more about choosing fans with solid rgb and potentially adding an LED strip.
You will most likely not need to update your bios. If you do then your new computer will not start up until you have fixed the bios so you will need another computer to download it and throw it on a usb stick