Unclued, in all those clues the wordplay gives the entry which is the answer minus a letter. The entries won't necessarily be real words. As to the removed letters, that's the key to the puzzle so I won't say any more at this stage.
I'm on the same page as you unclued. With 20 and 26d I have answers that parse but have more than one letter missing - either I'm completely wrong or something clever is going on that I'm too thick to see at the moment. My answer for 26d is what you suggest which could be made 'bores' with the addition of two letters.
Unclued - I was exactly there for a while and it was the “Noted Seb” clue that gave me the PDM that then cracked it open, albeit it was still hard yards from there