My input too.
1) One uses a card to pay for things, and gets a bill at the end of the month. Then you pay this bill via a check or debit card, correct? Yep. My CC is held at Chase, for example. I sign into Chase Online and can see my balance, then I can pay my CC off using a transfer from my checking account. This was seriously the #1 thing not explained to me in college that I felt dumb for not knowing once I got a card. Lol.
2) Switching to a credit card to get points will involve changing all of my autopay bills (netflix, gas company,etc.) from my current debit card to said credit card, correct? (This might sound preposterous, but that was such a hassle to change when my wife and I got married, I don't know that it's worth a couple hundred bucks in points?) You don't have to switch them. My gas company only pays from debit or checking transfer because they tack on extra to use credit; same with rent. I autopay car insurance, internet, amazon prime, and more from credit. It was totally worth the points and takes not very much effort with the internet.
3) Do you feel having a credit card has psychologically caused you to spend more [than using debit or cash]? No, because it was functionally the same as a debit card for me, and I DON'T look at my checking acct balance....so there was never risk of spending $1000, but my checking acct not reflecting that and therefore I go out and spend more. People who live paycheck to paycheck with their checking acct balance as their guide to when they have leftover money...they may struggle.
4) Did you pick a card and stick with it (maybe netting $300 - $500/pts/yr.), or do you card churn for more points? And if you churn, that means you are constantly changing your autopay card, correct? I picked two cards. One was Chase SW, which has a fee but credits me 6,000 RR points annually in the value that offsets the fee. I've kept it because I spend those points anyway to see family. If you didn't, it wouldn't really be worth the fee. The other was Chase Sapphire Preferred, with a fee, and most of our spending goes on it now. The value in points greatly exceeds what we pay for the card.
I don't churn because I don't know how much you can do that without affecting your credit score, nor if that presents a risk to you later (e.g. Chase sees that I apply and cancel cards within a year and turn me down for a new one?). I also like to pick a card wisely, then hold onto it to increase my available credit (for low utilization is a factor in credit scores) and length of credit history. My first CC was student card with a $1000 limit, no fee. I don't use it but once every few months because that credit history is so much older than my others. Therefore, I technically have 3 cards, but put most spending on 1.
Again, if you churn I would still hold onto at least ONE card rather than try to switch payment methods every few months...
5) has the work associated with managing the card(s) been worth the effort (extra spreadsheets, autopay changes, avoiding yearly fee, making sure to spend $X in first 3 months, etc.) I think you are making it out to be more "work" than it actually is. I can see my points value on both cards when I sign in to pay the bill. The rest is minimal effort too, when you consider that I don't churn. I would not start out using credit cards by churning. Pick something with a low or no annual fee that you can see maybe sticking with long-term and learn to use it first. After a year or so, you can evaluate whether you want to add/churn cards. Keep in mind if you live a very pared-back lifestyle, then you aren't going to reap the rewards as much as someone who spends $10K/month. In my mind, rewards are for money I'm already planning to spend, not something I try to "earn" by spending more (that's their marketing technique).
6) Have you been burned by having a credit card. i.e. you thought you would be responsible and use it for the points, but you had an unknown late charge, a dip in credit score, forgot to cancel after a year and got charged the yearly fee, etc? In other words, despite you efforts, have you been "gotcha'd" in any way by the negative side of credit cards? No, but remember accounts are usually easier to open than close.
If you use someone's referral link for some of these, they can benefit from extra points, btw.