Play 1-3 or 2-1 until you're bored. Don't kill the raid boss if it spawns as it can block the secret garden. That's pretty much the trick.
As for who to level, just pick whoever you like. The power between silvers isn't that much.
JP wiki mentions Yulan, Hinoki and Cyani in particular are outliers, but you only have one of those.. who shares the same type as Orchid.
Just do whatever imo.