I found this to be a truly first-rate puzzle by Imogen.
It took a while for me to get going with my FOI being 23a, although I didn't do myself any favours by putting the homophone rather than the answer in 24d! However, once I'd sorted that out, things began slotting in quite nicely.
I can't see any problem with 16a which makes me think I might be missing something?
Way too many COD contenders this week but if someone had a gun to my head I'd probably go for 18d.
I'd always thought that 2d was a term borrowed from our American cousins but, according to Chambers, it's actually theatre slang.
Thanks to Imogen for a stellar Prize crossword.