Trade-in has nothing to do with Applecare+. AC+ is an extended and expanded warranty service, trade-in is getting value for your old phone to put towards a new one - which model is up to you and you pay the difference.
If you have a better condition phone due to recent replacement, you might get a better trade in value but probably equals out with deductible.
Heavy duty velcro is your friend.
Just put some clear packing tape over the whole back of the phone neatly and trimmed a bit over the sides, just to hold it together so you don't get shards flaking off everywhere, and leave it in it's case, until you decide to repair or upgrade or whatever.
Not likely to damage the phone further, more injury to yourself and obviously the phone is not water resistant anymore, so keep it dry.
As mentioned panoramic images can go up to 60+ MP, because images are stitched together horizontally. MP count is relative to image size, so the MP count goes up.
Not so much looked over, it's just out of normal case use for most users. But I also don't see any harm in having more default options.
But anyway, you can use Zoom or Reduce White Point to achieve this dimmed display, with the latter being a bit easier, but both can be made very accessible with Accessibility Shortcut.
For the latter, go to Settings > Accessibility > Accessibility Shortcut and select Reduce White Point. Then go to Accessibility > Display & Text Size - then toggle Reduce White Point on, and set it to 100% or whatever level you require. Now you can just triple press the side button to toggle it on and off.
You can do the same with Zoom as well with Accessibility Shortcut, but with a few extra steps. You can even add both to Shortcut, and choose which one you want to use.
With Zoom, you can three finger triple tap the screen and toggle the filter there as well, with the popup menu.
It's more the quality of the cable really, common fault is internal breakage for example because they use less and poorer quality wire. I've rarely had any third party fail due but I buy decent branded but inexpensive ones. I've not had an Apple cable fail either, but have had cosmetic damage like a lot of people where the sheathing breaks off etc.