Re 1a, check out this page:
https://tinyurl.com/jefax565
Swarb, I found this somewhat unPaullike as well, but that’s a plus in my book. None of those extremely annoying clues split across multiple entries for one thing. I actually enjoyed this one. Like geeker I did struggle with 26 of course, but a map search gave me the right Devon town.
Add me to the list of those with 17 as COD. Still haven’t completely parsed 12, but I’ll look again in the morning. Very late here (California.)