2. I read somewhere that one should never store ordinary files on the same disk as a Time Machine backup. Is this correct? What is the risk?

Loren

I can perhaps answer a couple of Loren's questions.

I have a 750 GB external USB-2 drive running through a powered USB hub. This hard drive had about 90 Gbits of info on it (not Time Machine info) from a previous computer. (Both computers run Snow Leopard)

I hooked it up to a my current computer to use for Time Machine. The first 4GB of Time Machine backup loaded in 11 minutes which is about a third of a GB per minute. Things sped up quickly and I had 100 GB of Time Machine completed in 90 minutes which is a bit over 1.1 GB/minute. The total TM load totaled 200 GB, but I did not time the balance of the load.

All of the original data from the previous computer is still on the USB drive as well as the Time Machine info.

Ted