Can I add folder keyboard shortcuts? (like there are for Home, Downloads, etc)
It is indeed possible. To look at how, please read this answer – it's better than I could have explained.

Specifically, you would want to try what's written under the steps:


  To open a new window every time, add a Get Specified Finder Items action, drop the folder you want to open on the list, and then add a Reveal Finder Items action.


So in Automator you would add your folder as described above, and then carry out step 4, assigning whichever shortcut you wanted for it.