EMPOWERgmatRichC1) I would say that, especially in the quant section, about 1/4th are silly mistakes. This is a bit harder to indicate for Verbal
2) Some Quant questions I got wrong were indeed accountable to math principles I did not memorize. My main issues seem to be reducing very large root questions and questions regarding primes. Especially the parts with prime numbers and divisibility, everything in that corner is hard for me.
Regarding verbal out of my 11 mistakes, 7 are from Sentence correction so that's an obvious issue I suppose. Never been too keen on grammatics. My english is at a moderate level I'd say but I never really studied the grammatical part. I always 'follow my gut feeling'.
3) In the quant section only really 2 or 3 questions were just straight up too hard. While reviewing my other mistakes I almost immediately caught my mistake and understood why.
Verbal, again sentence correction. Those very long sentences really get me. Also the 650-700 Reading comprehension questions seem quite hard.
4) I finished quant section with 5 minutes left. Verbal was just enough time but had to speed up while I got near the end.
5) Not many honestly, maybe 2/11 or 3/11.