Do you think churches would have a better understanding of Apocalypse if they knew O.T. prophecies?

Absolutely! Many, but not all of the prophecies in the Old Testament concerning the Apocalypse overlap with those in Revelations. As well, there are many prophecies found in the Old Testament that Revelations does not cover, but are still necessary if a person is going to understand the "signs of the times." However, an obsession with such prophecies isn't healthy. Not only is a preoccupation with the future unhealthy, but there really are some prophecies that we just haven't been given the key to understanding yet.