I don't think Apple ever applied throttling to devices prior to the iPhone 6. As you say, old 5Ses would shutdown at 20% (or lower), but it was with the iPhone 6 and later where devices would occasionally stop at 50%, so became a much bigger issue. Presumably this was due to the A8 CPU having a wider-range of power consumption (this is a guess, if anyone actually knows why I would be interested to know).
For point 2, there is Coconut Battery on MacOS. This is telling me my old iPhone 6 has 90% capacity after 400 odd cycles, which is probably par for the course, but I have no idea if that's bad enough for the performance throttling to kick in or not. Hopefully the new screen is going to be detailed enough to say how much throttling has been applied.
For point 2, there is Coconut Battery on MacOS. This is telling me my old iPhone 6 has 90% capacity after 400 odd cycles, which is probably par for the course, but I have no idea if that's bad enough for the performance throttling to kick in or not. Hopefully the new screen is going to be detailed enough to say how much throttling has been applied.