Do I have to import all my projects?
Nope, not at all. You can import one at a time or all at once. It’s up to you. You don’t even need to import any projects - you can start from scratch with no projects in the all new Basecamp.
If I import a project into the new Basecamp, what happens to the project in Classic?
Everything that was in Classic stays in Classic. Importing projects into the all new Basecamp doesn't change your Classic account at all. You can even use both accounts if you'd like.
Do my users come over too or just projects?
If you import a project the people come with it. Users can sign into the new Basecamp with the same username and password they’ve been using for Classic.