The static blog pages though are all cached via nginx so I was surprised I needed to increase the nodes & relicas. Short answer is I don't know, and will need to investigate, but I suspect it's because the kubernetes node instances themselves are fairly low powered, there's a low cpu limit on nginx, and perhaps nginx is doing a lot of work serving the js bundle to so many simultaneous users, which really should be hosted on a CDN (probably also the blog).
Probably shouldn't. If you are already managing an automated environment, creating another environment that is easier to manage has nearly no upside.
Unless that phrase was meant to use the CDN you talk about later, but again, do you need a CDN to solve the easiest part of your infrastructure? (Or rather, do you have enough traffic so that it isn't the easiest part?)
I'm guessing he likes to tinker.