Thanks for asking, I was willing to explain those factors somewhere.
First of all, priority is totally based on my opinion and staff may feel free to change it. Traffic is purely based on view count. Most questions with high views still receive high traffic unless they were specific to a limited time period. Yes, priority and traffic are proportional, but the main factors which may increase priority is the relevance of the question. For example, a question about Legends: Arceus may not have high views due to being pretty new, but it'll have high priority due to being about a game everyone's playing.
I agree difficulty depends on where to look, and that's why I've put "depends on whether the information is straight up available or not" in some answers for difficulty. But for some questions like 'List of shiny locked Pokémon in USUM', the one about the event Sandshrew, or one requiring data mining, difficulty is pretty clear (being extremely easy, extremely hard and extremely hard).