Will organizer create a second file of all of my photos, or will it just set up addresses as to where they are. I have several thousand photos, and do not wish to end up with two sets of them taking up space.
Unless you have a mac and use the Import from iPhoto command, no. The organizer is just a database of your existing photos. (For iphoto users, organizer copies everything because writing into the iphoto library from outside iphoto could corrupt the iphoto library and cause loss of photos.)