1) Current Activity actions are defined in English only. It would be nice to have this changed just how you create Joomla Articles and link it to a language. Is there a way to add different languages?

All the language strings to translate the activity logged by CB Auto Actions are in the CB Auto Actions language files. GJ activity display is parsed and displayed by GJ so those can be translated in GJ (eventually all the plugins will be responsible for their activity access and displays).

2) When adding a new Activity it would be nice to be able to define who can see that specific activity. I tried to enforce that using the Integrations TAB and enabling Privacy but it doesn't seem to work.

There are no privacy settings for CB Activity at this time. It still needs API improvements which CB Privacy can then utilize to add privacy controls to activity. This is planned for a later release.

3) It would be nice to add a photo upload action to be posted within the Activity TAB.

Also not available and requires CB Gallery API improvements before this can be added. This too is planned for a later release.