Collaboration?

Yes, but you don't have a check in functionality. Be sure to have the same version of Captivate. You can provide your colleague with the cptx (or cpvc) file once you have finiished. Avoid working on a file stored on a networked drive however. I recommend to have a strong system for version labeling as well. As a consultant I often exchange files with clients, where developers do the regular development work, and I am fixing issues or adding functionality.

Be sure to use the theme functionality of Captivate: theme will be stored with the project, but can also be sent separately. Shared actions are included in the project as are advanced actions. The Theme colors palette can be saved with the project as well as all Preferences. About the theme:

What's in a Theme - a Template? - Captivate blog

Yes, we do it all the time.

If you use anything custom, shared actions, templates, they must be on both machines.