After the launch of project they wouldn't need as much marketing as for the ICO, did facebook ever did marketing ?
Yes of course they did.
You are only remembering facebook now and recent past. There were doing heavy marketing in the beginning.
They were? I thought it spread through word of mouth across colleges. In fact you had to have an e-mail address issued by a university. Or maybe I am talking about the very beginning.
I am quite sure they had nearly no avertisement and most traffic generated through WoM. That with the email at universities was in the very early beginning.