The default client you get with 1.1.0 is very old, and you should update by downloading Mercenaries Guild client or
TremFusion (which I use).
Backport is often used to refer to TJW client (also out of date by now) or any updated client which is backported/compatible with 1.1.0.
GUID is Global user ID and is automatically generated by the newer clients (stored as qkey file), it allows you to !register on servers and get admin levels.
To download mods, you need to set autodownload on with "/cl_allowDownload 1", on newer clients also "/sv_wwwDownload 1" for much faster download speeds. Could you be more specific about which commands don't work?
You can use "/unbind <key>" to unbind a button, but to reset? If you mean reset to default then I'm not sure it's possible without losing all settings at least for a moment. To do this, rename autogen.cfg to autogenold.cfg, start Tremulous (will have default settings at that point) & quit without changing settings, rename new autogen to autogenDefault.cfg and rename old back to what it was, then just open the autogenDefault file with notepad and search for the button, and copy that line to the end of your old autogen.
You should download the 1.2
gameplay preview and try it + give feedback about bugs (don't think you know enough yet to comment on balance), and you can continue playing 1.1 just by using different .exe/shortcut.
