There’s no need for Dropbox - syncing node_modules would be crazy (imho).
Learn git - it’s an absolute must know. Sign up for a free BitBucket account (free private repositories) and get a git client with a gui like Tower or SourceTree to learn with.
SourceTree is free, it’s made by Alsatian, the same folks who make run BitBucket. Tower costs $$, but it’s affordable and in my experience is a bit prettier and friendlier to learn with. They also have a nice set of tutorials, which is just a nice thing to do for people.
To start using git you only need to learn 4 concepts - commit, merge, push/pull, and branch.
Before you know it you’ll be using git from the command line because it’s so much faster, you’ll be telling the lady at the sandwich shop how zsh is better than bash, you’ll roll your eyes at people who prefer guis for anything, and you’ll hate seeing anything but text on your screen. I’m being silly.
Seriously, though, just think of it as a fancy version of save-as. When you’re finished working at home at like 4am you just push your changes to bitbucket, then when you get to work at 8am you just fire up your rig and pull your changes.
Presto, everything in sync, you have a complete history of your project, nothing ever gets lost, and now you know version control.
Seriously, just jump in and learn it. Using Roots tools and not knowing how to use version control is sort of like owning a Bugatti but not knowing how to drive a stick.
Those be my advices, best of luck to ya! 