Newbie Questions!

Hi, I wonder if you guys can help. I bought this little antique pencil for my wife recently and would like to get it working. It slides / extends and has a driver (?) pin that goes in and out so I think its functioning! A couple of questions I hope you guys can help with:
How can I make the ‘sliding’ to extend / close up smoother / easier?
What type / size of lead will I need?
Should the end with the ring screw off to reveal a storage compartment? Its stiff and doesn’t seem to want to unscrew but I don;t want to force it if it shouldn’t unscrew!

Any help / guidance would be very much appreciated. Many thanks,



I will throw up my bat signal for @Madrid!