If may one and only lore hero (no other hero has lore sphere) is the prisoner in escape from dol guldur, can I still play a zero-cost lore card (Rumour from the Earth or Deron's Runes)?

I am fairly certain you cannot. The hero is face down and as such its lore resource icon is not consider to be in play (in my opinion). You would have to wait until you've rescued the prisoner in order to play such events.