Hi ethereal
No - what sort of definition is "Shakesperean character"? There must be about a thousand! (Although I had, in fact, heard of all of them, and didn't need to Google.)
Yes, iit's tough to find them all, especially when they're only half as in 18ac. I still don't have15ac, ?O?O, 6d, ???E, and 5d, ???I?O. Don't know how to google them either.
6d is a currently popular girl's name. With another letter in front, it is a type of fish
15a "up" in this case means on horseback. It is the first half of a character's name