Does levelness of hive affect comb creation?
Yes. Especially if you are going foundationless. The way bees create comb is by hanging on to the top bar of a frame and dangling down in a “festoon” - like a curtain of bees. Gravity pulls the festoon downwards, so if the hive is not level in the left-right direction, the comb formation may well drift out of the frame. Front-back leveling is less important if you have your frames in the normal “cold” orientation, which you will in a standard Langstroth hive.