Does room level effect the the amount of damage deathclaws will do or how easily they can be killed?
From my experience, short answer is no.
Dweller levels, as much as that affect health pools, determine how much damage it looks like the Deathclaws are doing and Dweller weapons will determine how fast Deathclaws are killed. Higher levels/health pools make it look like Deathclaws do less damage, and stronger weapons will kill the Deathclaws faster.
With weapons that range between 7-15 average damage, I can stop a Deathclaw attack within three rooms, where each room besides the Vault Entrance has 6 people, all equipped with a weapon. But since they rooms tend to hold my newest and lowest level Dwellers, I have to use two Stimpacks on each Dweller during the attack before the Deathclaws move to another room.