You wouldn’t have 13 feats at a time, though. It’d be one at a time and you just get to choose which one. Perhaps could be further limited by only allowing changing once per short or even long rest.
But yeah, it definitely starts stronger than it ends. I was thinking the main ways it could sorta be used is as a jack of all trades, because you could probably have proficiency in any given thing so long as there’s no combat involved.
You did 200k years. You need to do 200k years as seconds (the 6.311e12 they mentioned). Their math is right.
Not sure why you’re acting like they claimed to invent the logarithm, either…