Will anyone be able to print to my printer?

Removing printer from search results

Select a printer in PrinterShare "Local Printers" list and click "Properties".

Here, you have an option to remove the printer from search results. This means that noone will see it in "Find Printer" dialog.

Rules to handle incoming documents

Open Automation dialog (Printer | Automation).

You can set a rule to handle documents from any sender (Anyone), or specifically for each user. You have following options:

If you are concerned that someone else might use your printers, you can set "Reject" as a default rule, and then allow printing to the required users only.