Can I program a direct short-cut (keyboard) for the functions "cursor to selected" and "selection to cursor"? Couldn't find them under the User Preference/Input tab. I know they're under Shift+S, but then I still have to select from the pull-down menu, and that is too cumbersome.
Bring up your snap menu with Shift+S.
Hover your mouse over 'cursor to selected', and then click on it with the RMB . You will see an option to either add or change the keyboard shortcut.
Hover your mouse over the box that appears, (it should tell you to press a key), and then press the desired shortcut one key at a time while still holding them down to create your new shortcut.
Make sure to save your new shortcut as defaults by going to user preferences by pressing Ctrl+Alt+U, and then save user settings.
In 2.8 and later, you can add a new shortcut to Quick Favorites which will give you a small menu with the keyboard shortcut Q
Simply RMB and select Add to Quick Favorites from the choices that appear.