- Regarding escaping, yes, you should escape anything you output.
Here is a short article from WordPress codex, explaining why and how:
2) Regarding prefixing, you should not prefix or suffix the handle for third-party libraries -> to avoid multiple loading of the same library.
Just think about a website having 20 WordPress active plugins. If every plugin loads the fontawesome library with its onw own prefix (1_fontawesome… another one with 2_awesome, another one with 3_awesome) then the fontawseome library will be included in that website for 20 times…
To avoid this, unique handles are preferred. Here are a couple grappler standard handles: https://github.com/grappler/wp-standard-handles
Also, maybe you could use for icons not the fontawesome library, but the built-in Dashicons library. Dashicons: https://developer.wordpress.org/resource/dashicons is already included in the standard WordPress installation. The result will be a performance boost you give to the website, by avoiding loading not neccessary extra icons:
There is also a tool named IcoMoon App, which helps you to generate a library of only those icons you need from fontawesome and other libraries (thus avoiding loading extra not used icons): https://icomoon.io/app/#/select/library