In the launcher, if you click the Data Folder button, it will open up the folder that has all that information. You can either back up the entire folder or just the parts you want.OK, this may have been discussed somewhere else...but I can't find it...
Is there a way to export all my characters at once so I can back everything up without having to export each character individually?
What about custom encounters / adversaries from the GM tool-is there a way to export those all at once as well?
This.
I routinely copy my data folder from my home network to my laptop (then point the laptop to the local copy) when heading out to a game session, then, if any updates are made, I copy it back to the network.
You can also perform a complete backup using the Data Editor. It'll put everything in a ZIP archive. If you switch computers later on, you can do a restore and it'll put everything back.
one could also put the data on a dropbox. or google box.