This reminds me of Hello Internet recently releasing a special 2-minute episode of their podcast on a wax cylinder - https://en.wikipedia.org/wiki/Phonograph_cylinder

Really difficult to get your hands on one but it's possible. And the peak of their popularity was about 100 years ago.

I'm guessing that none of these formats will be readable in 100 years. 9-track magnetic tape (remember those big tape drives on mainframes, starting in 1964? [1]) is already virtually impossible to read, and that's after it was out of use for only a couple of decades. And that was an industry standard medium with lots of important stuff on it, like data from NASA missions, old business software and backups, etc. Somehow it all got converted to other media. So I don't think any of today's media standards will survive anywhere close to 100 years, especially not consumer-grade stuff like CDs, DVDs, VHS and USBs. (Think of how hard it became to read a floppy disk just a few years after PC manufacturers stopped shipping machines that had floppy drives.)

[1] https://en.wikipedia.org/wiki/9_track_tape

I don't think circuits degrade that much over 100 years, now the electronic components (like capacitors) may need to be replaced, some plastic parts may also, but the devices could still be made operational. I guess besides component failure is the amount of firmware data loss over time (devices with EPROMs instead of ROMs) would be another factor, which might not be good for the more complex devices, then again such code might be backed up somewhere in a vintage device collector's archive.

I think so (if the data is still intact), although it will probably be very difficult to do with common equipment; you will need uncommon equipment to do so (which might be very rare by that time, and maybe not available commercially, but I think some interested people might make their own if needed, and do it anyways). (Even now there is people interested in various kind of historical stuff.)

"We" as in a normal person? Probably not. You'll have to go through a museum or a collector who has a functioning one most likely.