okay, so I am 10 steps farther down the path now..

If I hve a backed up version of the dat file, are there risks I should know about.. is it one time back up , .. or after each trasaction? ... how do I "USE" the dat file, I don't see a option to "import dat file" or "restore from back up" in bitcoin -qt

Oh, and 1 more question, . how do I find out the address that they "came" from .. or is that even possible ... seems to me that bit coin is "1 sided" in so far as you can see receiving addresses, be not "sending" address is this right?