I have a few questions on Time Machine. I'm using an external HD (time capsule) over ethernet. 1. How do I limit the total size of the space the saves take up on the HD (I don't want it to keep expanding, filling the whole HD, as it has to be shared with workmates with their own files). 2. How can I specify a sub folder? It just gives me the option to select the drive (not any of the folders already setup on it).