Version: 0.9.14 Easily keep track of the last time you interacted with your contacts.
Development is still ongoing. The implementation, interface, and feature set are liable to change, and if so, possible without regard to backward compatibility. The 1.0 release will signify plugin stability. However, feel free to try things out on a test installation. I welcome the feedback!
In the future, yes; an API will allow support for other contact services. At present, no; only Google Contacts is supported.
No. This plugin provides an interface for managing when you contacted your contacts. It does not provide a means for managing contacts themselves. By that I mean you can't add contacts, edit contact details, assign/deassign contacts to groups, etc with this plugin. Nothing you do ever gets pushed up to the contact service (i.e. Google Contacts). Use the contact service to manage your contacts.