fo light (ie photons) to be gravitationally bound by a black hole, or anything for that matter, doesn't it require that photons have some sort of "mass" even if said "mass" is in a different dimension that is not measuarable currently?

No, it is the SPACE that is actually curved- light is travelling in this space and thus is affected just like everything else- remember the famous eclipse observations that showed the sun's gravity bent light?

How is it that gamma rays can escape from a black hole but not photons?

First off, gamma rays ARE photons- gamma rays are light.... second they do not escape the event horizin of a black hole- black holes radiate gamma rays primarily from the accretion disk that surrounds the black hole... this accretion disk is matter that is spiraling in to the event horizin of the black hole- it is very energetic- the gamma radiation released is the 'death scream' of the matter falling into the black hole.

I've always thought of gravity as the effect of one mass on another...perhaps this is an overly simplistic view of gravity?

It is better to imaging gravity as the effect a mass has on the surrounding space when you contemplate the effect of large masses on light...