Finished, but can't completely figure out the cryptic wordplay for 16a and 9d - Enigmatist seems to go out of his way (I'm sure it's a him) to be obscure. Any help much appreciated.
16A Read all about means read backwards.
Technique = art, America= usa, adopting( with) variety= make. endless mak. the whole is artusamak. read backwards.
9D Gobsmackingly, except for king I too am confused