As for the rest of what you're writing, you seem to base yourself largely on Keirsey and the four temperaments, but in a discussion about Depp being INFP or ISFP, Keirsey doesn't really work. He focuses mostly on strengths and forgets to mention the typical weaknesses, and more importantly: INFPs and ISFPs have more in common with each other than they do with NFs and SPs respectively. Their shared Fi coupled with an extraverted percieving function makes them very artsy and creative and neither resembles an ESTP or an ENFJ much. Therefore it's better to use MBTI type observations and a dash of intuition rather than using Keirsey imo.
But you don't have time for this and the world won't fall apart if we can't agree on Johnny Depp's type, so feel free to continue believing he's a classical ISFP. We won't know for sure before he takes the test and tells us his results.