It should be pretty easy. The Apostles were directly led by the Holy Spirit and it not only showed in their lives but also it manifested itself in their acts of healing (lame could walk and blind could see). So any claims they have of direct succession would be readily apparent.
Spot on.
Yes, I’ve often thought the same thing, that the gifts that come along with prophecy should be manifest, if someone is receiving revelation from the Holy Spirit. Otherwise, anyone can claim they “felt” the Holy Spirit guiding them to a conclusion, and it would be impossible to distinguish from a subjective and fallible human thought or feeling.
It’s true the NT says different believers will receive different gifts, but the apostles possessed all the gifts, so those trying to claim the mantle of the apostles have a high bar to pass.