These are good questions. Apple’s RAW engine is quite limited in its lens correction. Mostly it works for fixed lens cameras (e.g Sony RX 100), micro 4/3rd and newer cameras like the Nikon Z series (I think). They don’t list which ones they support for this.
It’s unlikely that lens correction is being applied for your 50mm 1.8 but it might depend on the camera body. Perhaps there is a crop being applied – I cannot say without looking at the RAW myself.
Yes, RAW Power will detect if lens corrections are being applied. I hope to do more with lens correction in the future, but I do not know for sure what my plans are.