Because the positions are vastly different, the qualities they would be looking for also would be different. However, great communication skills always help get the prersonal connection going, that's important. And what sets apart great applicants is that they GET it from the start. They understand the meaning behind your question, so they answer right away instead of you spending ten minutes and five questiong guding them to the right thought process. They KNOW what the issues the field/department/profession/industry are facing and what they personally can offer to help address those issues.
Very. On both sides. When I came as an applicant, I only came for two days so I had to fit 12-15 interviews lasting 30, 45 or 60 minutes into each. I would literally just fall asleep in my hotel room after I was done, forget the dinner and the intent to prepare for the next day's interviewes. As an interviewer, it was a little easier, but still exhausting to see some ten-twelve people over three days while trying to attend relevant sessions as well... There are all those networking events at night too, worth attending if you get invited. Never know who you might meet.
Do yourself a favor and don't write one until AFTER the Midyear. You can (and, depending on your self-awareness and writing skills in general, maybe should) start jotting down ideas which are related to yourself and what you can bring to the table - that will help you with the interview prep process - but don't write an actual letter. If you write it now, it will be generic to the point of being useless. When you interview at the PPS suite, you will learn what people you interviewed with consider the most important - and be able to address those points in your letter. Besides, you might not even know which fellowship(s) will end up being your top choice(s). That was the case for me - my top choice, which I ended up completing, was not high on my radar before the PPS, it was actually the third and final interview I had there which convinced me that it was the one.
