(This is assuming a 1.4 installation – but I suspect the 1.3 as far as repository location)
If you look in the custom-data-location.properties file it will tell you where the files are saved. The properties file will give you the path and directory of ALL your files.
If you did not change the default settings. Go to the root directory of your alfresco installation. Then go to the alf_data directory. That is where all your files are stored.
Once again, go to that location to see the data stored on the fileserver.
As for what is stored in the database and fileserver. Any file that is uploaded, meta-data is extracted and much of that is stored in the database. Alfresco does this on it's own, and I suspect it is different based on the kind of file you upload (e.g pdf, .doc, .txt, etc..)
To get in to more detail, you would probably need someone from alfresco to tell you what exactly is stored in the database… But if you just want to see where the files are stored, go to the location I referenced above.