1. No, the data from that computer remains available for historical purposes. Interface could be rewritten to let you flag stuff as not visible, but then people would want to be able to see them sometimes, so goes down a longer complicated (i.e. time to write) path.
2. Loader service, this actually loads tbbmeter, on Vista and newer and avoids the annoying UAC pop-up that would otherwise happen when the software started on every reboot. The loader service should appear first and once the necessary bits of windows are running it will start tbbMeter.