Well as far as what I meant by balance, they do indeed have Castlevania elements mixed in with the new design. Now keep in mind this is just my opinion of the game and what MercurySteam has done with it.
Sub-weapons: So far we know that you'll get the dagger and holy water subweapons in the game. That is traditional Castlevania.
Belmont and the whip: As you stated this is another thing that would make it a Castlevania game through and through.
Breakable candles: I know that's minor but it's still traditional!
Familiar bosses: Some of the bosses from older Castlevania games make a return here as well, albeit looking somewhat different. (Malphas, Slogra, Death, Brauner, Carmilla, etc.)
Backtracking after upgrading abilities: This is moreso from the recent Castlevania entries but that is also in this game as well. Certain spots require you have an ability that you would otherwise have at a later point in the game.
And uhm...well...a Castle. A few of them in fact. I'm sure there are other similarities but that is just what popped into my head.