GridBuilders, Searchers and Where to put them

Hello,

I was looking at the Cabana sample app, and was wondering about the GridBuilders. There are many GBs in the Foundation project (Source\Infrastructure\Foundation\GridBuilders), and then there are some in the individual UI Modules (Source\UI\Products\GridBuilders).

My questions:

1. Why are they distributed like this? Is there a reason?
Are the GBs in the Foundation project for use throughout the entire application, whereas the UI ones are only for that individual module? Or something else? Or is this completely random?

2. Is there a strategy I should be using when I create my GridBuilders?
Where should I be putting the "Entity default" GBs - in a UI module or in Foundation?

3. Does it matter to the Searchers where I put the default GridBuilder for an Entity?


Thanks!

Heather