That adapter looks pretty neat for us people that juggle a whole bunch of disks every now and then. I think it's been mentioned here at DC before.
Haven't looked into CacheMan, but since it includes a "optimize RAM" feature I'll stay away from it. Some of the cache-related tweaks it can make are worth investigating, but I wouldn't keep the program "running and tweaking".
Quick Format is faster, Full Format gives the harddisk a bit of workout. I tend to do full format (and with the bootcd/floppy/usb/whatever tools from the HDD vendor) when I get a new harddrive, and then mostly stick to quick formats because, well, they're faster. Every once in a while if I need to do major changes, I'll do a full format to give my drive a bit of excercise.