You can use google earth offline all day as long as the info is stored in the cache (2000mb limit). As for topo's, I'm not looking to link up to server, I'm creating image overlays that are linked to my harddrive so that they are used offline which I have done successfully.
The problem is that with image overlays, you can only use a photo no bigger that 2000x2000. This is smaller than a topo map so that requires cutting and lining it up. I was trying to see if there was a way that set a grid or another type of overlay so that it can pull up the full, hi-resolution quad instead of slicing it into quarters in order to make it fit.
Example - When you use the USGS Topo kml, it brings up a grid and you choose what quad you want. It doesn't load up a full resilution picture right away so it has me believing that it uploads a more detailed image depending what your altitude is set at. I haven't had a chance to tear apart the file yet to confirm this.
