Great machine, great price. The owners manual is always an excellent place to start research:
https://archive.org/details/Form21.S...erentMaterials
The W&W Yahoo group is also very good for history and any further questions beside the QB
https://groups.yahoo.com/neo/groups/...-Machines/info
You have a W&W model D9 which was made by W&W from 1895-1905 and then continued by Singer for a few years after 1905 when they purchased controlling interest in W&W.
The main trouble or minor inconvenience with using the D9 is locating bobbins and needles which are both no longer made. The bobbins aren't cheap but can be found online and so can the needles which are most commonly termed as 127x1 or Boye 18. A modern industrial MY1014 round shank needle can be used to save a few bucks but doesn't have the flat like the originals for orientation.
The D9 handwheel turns away from the operator which was more common with the antique machines.
Good Luck
Jon