Pretty much the same as last month really, 6 Megas (whether they include Kanto starters I'm not sure, but 6 either way) then 3 new Pokemon probably the Kalos starter evos. Characters I hope they stay clear of unless it's a bit more info on Alexa. GL info is a big NO! Hopefully a bit more on Character customization and obviously the fairy type chart.
If it is a separate book, I'm interested to see what it is about. One thing I'm worried that, if Rick is writing this at the moment, and it ISN'T the next HoO, we may have to wait another year for the next book, if there is one. Unless he has some serious multitasking skills and can write 2 300-ish page novels in a year.
Besides, I can't imagine a Greek Mythology book by him that isn't in the Percyverse. (That's a fun word to say )
YES OH MY GOD IF THEY DIE IN TARTARUS I WILL VERY BAD THINGS
The Singer of Apollo, huh? Maybe it's the 5th book of Heroes of Olympus? They all seem to be in the format of "The ______ _______" or "The ________ of __________". If it is, I'm interested to see how Apollo plays into this...