CEV Payload

Question about the future NASA space vehicle that's supposed to replace
the space shuttle:

Will this thing have the payload capacity of the current space shuttle?
I was always told you could fit a school bus in the payload area of the
space shuttle. With the current shuttle, don't they put a lab section in
the payload compartment or a satellite to be launched and a mechanical arm?

I've seen a few diagrams of the CEV on the net. But all I've found are
the diagrams of the main area were the astronauts sit and operate the craft.
I have not seen any area where they could put satellites and such.

Is this thing going to have a lab/living area and mechanical arm? Will
they be able to do with the CEV what they can do now with the shuttle?

If they plan on sending this thing to Mars in the far future isn't it
necessary they have a big lab/living area?

Thanks!