2. The Options available here affect the whole Rhinoceros program. You can adjust these to suit your own taste, but the Nudge steps in units section needs a bit of explanation. I will be using a British aircraft prototype, so will be using feet as my units of measurement. The nudge keys allow me to move selected items by these set distances. Nudge key alone is set to 1.0, or 1 foot. 0.08333 is 1/12, so by pressing the Ctrl + Nudge key, my selection will move 1 inch. 0.02075 is 1/48, so when I press Shift + Nudge key, the item will move 1/4 of 1 inch.
Of course, if your subject was made to metric dimensions, these settings could be 1, 0.01 and 0.001 for meters, centimeters and millimeters.