I (probably many others too) assume the Heroes Characters are going to be the new characters introduced in Book 2. Also here is hoping for another Eliwood card.
I'm casual so I don't know if my advice will help but I sometimes use Sigurd 4/3 from the Starter Deck for his +10 skill active (need Sigurd in bond) and Seliph 5/4 with his +10 skill active helpful against more powerful decks.