1. These "safe" generic font types will make your text readable on all systems using Netscape 4. The other columns list fonts that will not be available on all systems. In fact, if the font doesn't look different from your default font, then that font isn't available on your system.
2. The last fonts are True-Type Web fonts available from Microsoft.
3. You can edit the contents of the output field directly, and then press Set again to reset your type.