If I installed node/gulp and git do I even need to use homebrew -if so what are the benefits?
What would happen IF I did?
Would I have multiple versions of node/gulp/git floating around on my machine?
Ideally should I uninstall them in order to manage them with homebrew
I'm just learning so I can get react running
In your case, it's better to uninstall the manually installed versions of node, gulp and git and to reinstall them through homebrew.
You can then upgrade them all in one command with:
brew upgrade
and uninstall them cleanly and easily with e.g.:
brew remove node
The main interest to have a packet manager is to easily upgrade all your software and to manage them all with a single set of commands.