Yes, it absolutely is. You may commit files to a database or a file system (or IPM, which is not exactly the same app as WebCenter Content: Universal Content Management).
In fact, quite on the contrary, everything runs solely on Capture's side and only during commit you link Capture's metadata to UCM's ones.
What jiri is saying is that it is not necessary to have webcenter content (UCM) to use webcenter Capture. There are many commit drivers available in webcenter capture, you will choose your commit driver based on your repository where you want to store your documents.
No, once again, File Cabinets, Scan Profiles, Index Profiles, and all other settings are defined solely in the WebCenter Capture. If you commit to file system, for instance, you may create a flat file that will contain metadata as entered/recognized in the Capture. Only, if you commit to UCM you may define - as a part of your UCM commit profile - links between UCM and Capture metadata. In fact, if you don't do that, the commit may fail.
Yes it is entirely possible. Jiri is right when he says that it all depends on your configuration.
WebCenter Content usually comes into picture after Imaging receives the file/files committed from Capture/Forms Recognition. Else when you configure direct commit to Content, but that doesn't look to be your requirement.