Hey Reaper - great questions and you triggered a bunch of awesome stuff. Perhaps like drinking from a fire hose for a bit. Biggest advise stated (which I agree with) was: Take a bit of time and get educated. Read a LOT. It'll be overdose and "too much" for the first bit until the pieces of the puzzle come together.
Here's a Canadian couple.. yes they were high income earners but they REALLY really dove into things and created a great "how to" online guide for free. Website link is here:
https://www.millennial-revolution.com/start-here/, followed by:
https://www.millennial-revolution.com/investworkshop/
and their basic layout is as follows:
Part 1:
Why People Lose Money in the Stock Market
Part 2:
How To Build a Portfolio
Part 3:
Asset Allocation: Slicing the Pie
Part 4:
Rebalancing: How to Buy Low and Sell High
Dollar Cost Averaging: How To Invest Without Freaking Out
Sequences of Returns Risk
Black Swan Events
How To Pay No Tax On Your Investments (Canadian Edition)
Investment Fees Are The Worst
I have *not* actually rigorously followed this specific instruction (but do in general), but have followed their online blog and studies etc etc pretty much since the beginning. It may be easier to binge-read some of this stuff.