it's my opinion that HY embryology doesn't add a whole lot to first aid. (i read the longer version, which actually doesn't take too long) FA is pretty comprehensive as far as the basics go. obviously it's not complete, but it's a LY subject like you mentioned so if you're gonna go OCD then channel it to something more HY like immuno. i annotated maybe a few words here and there for embryo, and took some images from my school's embryo textbook. (mostly heart stuff)
and yeah, you gotta know the branchial arch, pouch, cleft stuff, as well as the neural crest derivatives. those probably come up on everyone's test. don't get too crazy with the arch stuff, just knowing the basics like arch 1 has Ms, arch 2 has S, is good enough for most cases. no guarantees though obviously.