I want to know if I can use my custom fonts in Google Docs or any other Google Drive products.
You have to set the language of the document first under File > Language, and a font selection menu option will appear.
You can't directly add a new font however, as fonts for use on Google Docs are powered by their Google Web Fonts service. You can only add fonts that are listed on that service. Instructions on how to do that are here http://support.google.com/drive/bin/answer.py?hl=en&answer=189190