Modern Warfare 2 One Steam Pre-order

I want to get the new Modern Warfare 2 on steam rather than but I have a few questions. Will we still log into our Activision/Blizzard account? Also I want to Pre-order the Vault Edition that will come with the 12 Ghost skins, usable in Warzone. Will I be able to get these skins on my even if my pre-order is on Steam? Sorry if this has already been answered.