If you have many functions which go good together you can put them as a *.plugin.zsh file in the @custom/plugins/@ directory and then enable this plugin.
If you would like to override the functionality of a plugin distributed with oh-my-zsh, create a plugin of the same name in the @custom/plugins/@ directory and it will be loaded instead of the one in @plugins/@.
If you want to uninstall it, just run @uninstall_oh_my_zsh@ from the command line and it'll remove itself and revert you to bash (or your previous zsh config).
I'm far from being a zsh-expert and suspect there are many ways to improve. If you have ideas on how to make the configuration easier to maintain (and faster), don't hesitate to fork and send pull requests!