Please help another moron.

[Icarium81]

Just picked up a Raspberry pi 4 model B 2gb, the guy I bought it from put retropie on it for me. Aside from that it's brand new.
My only goal is to have it play NES, SNES, and other old systems.

The little research I've done shows that the pi is likely formatted for LINUX, which I have zero experience with, and putting the 16gb SD card( also likely formatted for Linux) into a USB reader on a windows laptop it shows an available space for 255mb)
Upon booting up the Pi, it requests I set up a controller.
Tried Bluetooth syncing an Xbox series X controller but no luck, I do have 2 wired USB Snes style knockoffs coming.

Keep in mind I'm a moron, you can't possibly dumb it down enough for me, I won't feel belittled lol. Gotta start somewhere and something interactive is easier than reading random possibly wrong info on websites.

So my questions are these
1: optimal way to start my gaming.
After the wired controller setup, what will I be looking at and how is it navigated?

2: Best place to store the games? On the included, removable 16gb SD card?(the one from above)
OR on a USB drive.

3: Upon knowing where to put said files, is there a specific directory/paths to put them?

4: Not retro emulation related, but after likely a few years, I'm wondering if this Pi is capable of running some old school 486 games? Very very specifically Might & Magic world of, and Dark side of Xeen, (combined the two games make World of Xeen)
I don't care in the slightest about the audio, only that the game plays.

ANY other basics that I should asb about but simply don't know about yet that I should likely be walked through?
Thanks in advance, an older guy wanting to play play super mario world
Old enough that I can remember a fair chunk of navigating Dos, but zero knowledge of coding in any aspect.

[Icarium81]

@Icarium81
After a few hours this morning, I plugged in a keyboard via USB, and was able to navigate VERY VERY MINIMALLY, literally "emulationstation" and then made it so retropie auto boots without needing a command to do so.
I was able to get the retropie to recognize that there was a controller connected, by going into it's settings and connecting it via Bluetooth. (This was done by going in to retropie settings and that dumped me to a bios looking screen [not sure what that's called in Linux terms] and to have that connected there.
However this did not allow me to set it up in retropie (go figure).
All it does is recognize that there's a controller connected, nothing more. Can't configure anything though, it doesn't go past "hold a button to set up"
I've loaded roms on to the micro SD card, ONLY in a directory "snes".
Done similar to a USB stick, 4gb, in to both the main drive (no folder) as well as into a folder for each game AND also in a folder labeled "roms". Again in this roms folder I've loaded all 20 ish roms directly into the folder as well as in to sub folders with each games name.
NONE of the above worked to have the PI even notice that they were there.

So please assist me, the "progress" was made with a YouTube video. Certainly didn't have any epiphanies overnight lol