Re: Would gravity waves increase in proportion to increase in mass-

You're absolutely right on the first part of your question. 

Gravity waves are caused by the acceleration of a mass just like
electromagnetic radiation (also wavelike) is produced by the acceleration
of a charge. The greater the mass, the stronger the gravity wave. 

The second part of your question is interesting. You seem to be saying that
there could be a black hole which swallows even its own gravity waves.

It's true that even massless photons can't escape from beyond the event
horizon of a black hole. Also, the gravitational force is propagated by
gravitons which are similar to photons in that they are massless and travel
at the speed of light. Thus, gravitons originating at the center of an
accelerating black hole might be bent back in the same manner as photons. 

To me this sounds quite plausible, but I think you should run this by a
particle physicist. There may be some asymmetry between photons and
gravitons that would cause a difference in the behaviour of the two
particles in a strong gravitational field.