Streaming data in TGEA and TGB?

From several posts I have the impression that you can stream data in TGEA (geometry, textures) to make large exteriors or to avoid loading between small interiors. The main problem being how to determine what to stream.

Is this true? Can this be done in TGEA out of the box?

I'm interested into a TGB implementation and it's not just a fancy feature for me, but absolutely necessary. I need to stream textures and unload those not required anymore.

I don't think this can be done in TGB out of the box. How many days would a professional coder whit both sources (TGEA and TGB) need to implement this?

1 week? 1 month? forget it and love TGB for what it is and not what you want it to be ;) ?

Thanks for any insights!