Hi, guys, thanks so much for your replies. I found where to find the most up-to-date Samsung USB drivers for my phone at samsung.com/us/support/downloads/ (before I had used developer.samsung.com/galaxy/others/android-usb-driver-for-windows, which seemed pretty out of date -- more than four years old!). By the way, Sammobile.com offers downloads for Odin directly off of their servers, which I thought was kind of surprising too considering how mainstream the website is and the leaked proprietary origin of Odin. Guess they're not too worried about it lol.
I updated to the latest firmware/baseband version for my model though. However, my process had me wondering if doing a factory reset in stock recovery kicks off the USB debugging mode ... does it not? (Since of course, if you enable it, then do a factory reset and system reboot, the dev. options + the USB debugging mode is disabled again.) But my process was to 1.) enable USB debugging, 2.) reboot into recovery mode, 3.) factory reset, 4.) reboot directly to bootloader, 5.) then finally to flash the latest stock firmware via Odin. Everything seemed to go smooth, but that had me wondering if the USB debugging gets disabled in recovery mode after a factory reset (since it does for sure at least after the first system boot). Is it not best practice to also do a factory reset before flashing a new ROM/firmware?
Thanks again!