For a font to be available in applications you must have the font file in your system fonts folder. On a Mac running OSX the Library folder contains a font folder. The best option is to use a font...
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You can download fonts from websites such as .dafont.com
If you want to read .pdf files, yes you need to install it.
most scan programs allow you to save scans as pdf but it depends on the program. In the end you would need adobe to view the file