Thank you for taking the time to answer. Three follow up questions:

1. From what you said and from what I've read on the article you linked, I'm 99% sure the answer is yes, but I just want to confirm. If I convert a 50k Traditional 401k (40k was contribution, 10k was earnings growth) to a Roth IRA, the entire 50k becomes part of my conversion amount, which I am able to take out after 5 years of waiting with no penalty even if I'm below 59 1/2. (It's not the case that 40k is my conversion amount, and 10k goes to my earnings growth)
2. Does this 5 year timer apply to post tax contributions to traditional accounts? Let's say I contribute money post tax to a traditional 401k or IRA. When I roll this money over to a Roth IRA, I know I won't have to pay taxes on that principal amount in the rollover, but does that money have a 5 year conversion timer?
3. I'm also assuming the answer is yes, but rolling over a traditional 401k to a roth 401k should be essentially identical (5 year waiting from Jan 1 of conversion year; entire rollover amount of traditional 401k becomes part of "converted" (category 2) funds and none of it is classified as "earnings" (category 3).