Not strictly necessary to remove this end of the cable, as the other end is also disconnected later. However, it does get it out of the way.

During disassembly, I found it easiest to disengage the bottom/connector side of the cable bracket clips first, then pivot up and pull away from the frame of the laptop.
If reassembling with a new display, the ribbon cables can be very stiff on the connector end. I found it easiest to first install the press connectors (step 28), then use the flat end of a spudger to gently coax the ribbon cables around the curve on the top edge of the screen cable bracket buffers until I could engage the top clips of the cable bracket. While holding the top edge of the cable bracket, I used the flat end of a spudger to gently push the connector end of the ribbon cables down into the gap, then engaged the clips on the bottom edge of the cable bracket.

The official repair guide recommends opening the lid of the laptop and setting the laptop keyboard side down on the edge of a table with the display hanging over the edge, then removing these screws.

Use low setting and heat until it's warm. You should be able to touch it comfortably. If the adhesive is still being difficult, alternate between heat and trying to remove

Tip: Be super patient with the battery. Put ~5-10 drops of alcohol on each side of the battery, then wait 5 minutes. Put the opening picks on the right side of the battery and very gently pry up as shown. If the battery starts bending, wait some more. Once you have the picks underneath the right side of the battery, pour another 10 drops of alcohol where the picks and battery meet, and slightly tilt the phone in all directions to allow alcohol to flow under the battery. Wait another 5 minutes. Gradually work the picks underneath and around the sides of the battery, reapplying alcohol and waiting often.

To avoid applying too much alcohol, gently tilt the phone and check the sides of the battery tray. I was able to change the original battery with no damage to the adhesive or bending the battery this way

Agreed. And if the sound post falls over, good luck.

I would also debate the claim that this is one of the most essential tasks, and one that every violin player faces.

The charging port assembly is removed in step 7. Simply follow the guide to step 7, replace the charging port assembly, then reassemble the phone.

For best safety the phone battery needs to only be under 25%. The phone will say 0% and shut off, but the battery is not fully discharged. Completely discharging lithium ion batteries has the possibility to do serious damage to the chemistry, reducing its lifespan or capacity, or causing it to refuse to charge again.

I've edited the guide to mention this as well, but isopropyl alcohol (ideally high percentage) will soften most phone adhesive, making it significantly easier to remove.

Both are “correct” as these are likely slightly different revisions of the same device. There seems to be a version of the device that comes with USB-C as well.

If you open yours up and find a battery without the metal frame, be sure to use care when removing the battery. Isopropyl alcohol helps soften the adhesive.

They can be purchased as two seperate pieces, but I highly recommend buying the complete assembly instead of fiddling with glueing them together.