That's how the profile tab already behaves. As for Joomla menu item that's also how the "My Activity" menu usage displays. When you are viewing your own activity tab you'll see your activity, your connections activity, and activity posted directly on your wall (this is also what My Activity page displays). When others view your activity tab they will see your activity and activity directly posted on your wall.

CB Activity 4.0.0 is implementing an Assets usage like CB Gallery as well so you'll be able to have as many activity streams as you want.

So when will CB Activity 4.0.0 be available?

When it's done, sorry we don't provide release dates here. You can monitor progress on our forge below.

forge.joomlapolis.com/projects/cb-activity/issues

But is there any way of incorporating the CB Wall so it will show up on feeds?

CB Wall? I'm not sure what you're referring to, sorry. Current CB Activity provides the Activity tab which displays your activity, your connections activity, and the activity directly posted on your wall. There's also a My Activity page that displays the same. There's a Recent Activity page that shows everyone's activity. If you need an activity stream with a specific asset and to be unique to that asset you can't do that yet as that functionality is only in CB Activity 4.0.0, which is still being worked on.

And perhaps to allow users to post pictures, videos, and links in the CB wall function?

There is no functionality for this directly on the wall yet and won't be in CB Activity 4.0.0 as it's functionality CB Gallery is to provide. Uploading through CB Gallery should generate activity though if you've CB Auto Actions installed and the respective System Action enabled.