Have FFG dropped any hints about what they might have in store for us this year?

other than seeds of corruption for the app? no.

Are any of the current monster packs 'monsters only?'

Definitely don't need anymore Hero's atm.

Nope, all have 3 monster groups and 4 heroes. Some boxed expansions don't have heroes (Mist of Bilehall, The Chains That Rust), but that doesn't make them better value.

Cheers, I knew about the expansions. My pile of unpainted heroes is already too big and cant face more lol

I've got Visions or Dawn, any recommendations for other M&H packs?

Just pick monsters you like the look/theme of.