Originals are not being fed into the fax.

Here's a longshot, you probably fed it upside down faxing the back of the document. I know, I've done it too.

This manual is only available from Canon dealers at an outrageous price. Better you just ask specific questions about it here

First you have to lift the panels under the speed dial numbers to expose all of the additional features and setting buttons, Press the REPORT button, then the SET button. This will give you a daily log.

chek the paper sensor

Open one-touch speed dial panels. Press 'Data Registration' button. Press 'Set'. Arrow down until Date/time is displayed. Press 'Set'. Make required changes. Press 'Set'. Press 'Stop' to return to standby mode.

Groups cannot be edited, you must delete and re-create a group.

If you are not a tech you cannot fix this yourself normally - it is usually either the fixing unit that has failed or the laser. You can try resetting the printer by entering the service mode ('data registration' button then press the # key) then scroll through to LBP reset (i think you select no. 6 for 'CLEAR' then select 'LBP CLEAR' or 'RESET PRINTER' and perform that. This may help for now.

You cannot edit GROUPS, you must delete them and then re-create a new group..

I don't think you can use as a printer. Only fax and copy

Fax machines are analog devices and will not work reliably on a digital phone line no matter what you do with any adjustment.