No, the battery is not trapped under the logic board. Moreover, that connector is under the logic board, but not blocked from sliding out by screws. The only reason would be to prevent the logic board from getting dissolved by the adhesive remover. Also, if you nudge the connector up with your finger, you can slide the entire battery out. If you only pry at the battery and don't intend to use any alcohol or adhesive remover, you don't need to remove the board.

Yes, the two iMacs have very similar layouts, so the PRAM battery layout wouldn't be any different

Wait till you see the MacBook Pro 2013-2019 battery replacements

No the microSD card is the one that contains the songs.

I'm gonna replace the battery instead when it goes kaput.

Is there a way to replace the battery without removing everything? I can just slide the big battery out of my Dell Latitude E6500 and pop another one in. However, can I replace the battery in my 2019 MBP 16" without having to remove everything?

I don't quite agree. I mean, I can just remove the glued-on lower case with a screwdriver in a few minutes. I would give it a 7/10 score instead.

I repaired my Casio fx-300w, a similar calculator with similar buttons. My mother, who gave it to me, spilled coffee once when using it in her office. I got rid of the sticky coffee gunk formed nearly 12 years ago.