My understanding is: Instead of calculating GI or GR for each and every frame, it gets calculated for the whole scene once and can be quickly rendered for all frames in that scene after that. Is that about it, or am I way off base?

yep instead of redoing it every single time you do it once and then move your models around/re render/animate in the previously made gi "environment".

Ok, I understand that part, now my question to you or anyone is this.... Lets say you have a scene with only polygon objects (my understanding is that one can only bake GI/GR to polygon objects)and you bake the lighting on the objects, does Vue ignore calculating the lighting (GI/GR Lighting I mean)on the objects baked, or do you have to click the "Ignore Indirect Lighting" button for all the objects with GI/GR baked onto/into them. I am just not not sure if Vue calculates the lighting on the objects, regardless of IL/GR baking if you are rendering a scene with polygon objects as well as trees etc...