Put
FONTS (files ending in either .otf or .ttf)
into the "Fonts" folder within your Library folder.
You can open these folders by double-clicking them and move font files manually into these folders.
You don't need to restart the Mac to use new fonts. However, you may need to restart certain applications (like "Word") for them to properly recognize the newly installed fonts.
Put (software)
KEYBOARDS
in the "Keyboard Layouts" folder.
Such files end in ".keylayout" (single file) or .bundle (single file plus associated icons).
Go to Activation and Keyboard Menu (DE)
... and they work on an iPad, too!