I ironed out a couple of issues (that were specific to my old phone - I had changed my google password, and the stupid thing had the old one cached somewhere so the market wasn't working). I then found the SD card, and then I updated all of the apps to whatever is latest in the market.
The good news is that the new caching capability appeared even through I was running Android 2.3.x. It seems to let you store up to 6 tiles, each one of which can be roughly 7Mb in size. The largest tile that I created was about 20 milesx20 miles, which seemed rather large. It is possible that in areas with more detail that the maximum size of the tiles would be smaller. I was able to turn off WiFi and browse the area, and it seemed about right - the maps got really blurry outside of the square. And as you move further and further away from the tile, the blurriness gets worse in discrete steps.
One other general comment about phones - they don't like to get wet. If you get enough water on the thing, it will kill the thing and it cannot really be repaired. This isn't specific to Android - an iPhone or most any other phone is like this. If you want to mount the thing on a handlebar and it might rain, you ought to have a plan-B of some sort (a ziplock bag maybe) where you could store it and keep it dry. If you need something that would work in a downpour, you probably need to go to a boating supply store and get a GPS unit that is designed for a marine environment.