An interesting tweak that occurred to me regarding how quests interact with research:

Instead of having generic research targets that unlock lots of quests at once, what if entering an unexplored high-level quest unlocked a unique technology that would allow you to complete the quest?  For instance, entering the Mines of Moria might produce a technology called "Speak Friend, And Enter".  Researching it would give you the ability to enter the quest location and complete it.