Have you seen my feeds & speeds page and if so did you turn away because of the math ?
The reason I am asking is because I wrote this after spending countless hours (and a fair number of reading and writing posts in this thread) myself to answer those same questions (or at least find something I would be comfortable using myself)
It looks bad, but it boils down to very, very little math:
https://shapeokoenthusiasts.gitbook.io/shapeoko-cnc-a-to-z/feeds-and-speeds-basics#wrapping-up-suggested-process
And even that is taken care of by the spreadsheet
https://shapeokoenthusiasts.gitbook.io/shapeoko-cnc-a-to-z/feeds-and-speeds-basics#calculators
Basically: pick a tool diameter, pick a material, look-up target chipload, input RPM, boom, get feedrate and DOC
EDIT: but it’s still a coarse grain approach. For figuring out the optimum between two different species of hard wood, then experiment, as @WillAdams pointed out