And I didn't start out 100% certain.
Whew! I had let the insulation point drop earlier because JonF's statement had me thinking I was wrong. I think we agree here, although my wording may not have implied it; There is some "old" heat trapped in the rock due to insulation of surrounding rock. And while it is a slow process, that heat does escape.
yes.
Would it be proper to say that this insulation process occurs in "pocket" regions within the Earth, or is it uniform throughout?
Uniform -- in general. However there must be some variation in the insultation from place to place. It is, in the details, messy and complicated.
Also, is it proper to say that the surrounding rock will also remain "warm" while the insulated "pocket" is cooling?
Yes. In fact, I would think that, since the bulk of the Earth is much bigger than even a large pluton and the heat flow is about constant the temperature of the surronding rock will, in the long term remain steady (some temporary local heating because of the hot rock in it).
Are the above statements a description of conduction {convection being heat transfer within a fluid)?
This is ALL to do with conduction. When you get lower down (below the crust) then we start to consider convection. We are talking about surface (or near to it) rock formation so there is, I think, more conduction that convection.