MetroPoint Questions

I have a customer that currently has two sites within the city with VNX 5500's, VPLEX 5.1 using Metro for active-active configuration (Sync).  The configuration is such that half the environment is split between the two sites.   Thus Site A is recovery for Site B and Site B is recovery for Site A.

They have a third site "C", that is over a 1,000 miles away.  It too has a VNX5500.  It is connected to Site B via a pair of RP's at both sites.  They replicate a small subset of volumes from Site B production to Site C.

They are interested in MetroPoint.  So I have scoured the various sites for both RP 4.1 and VPLEX 5.4 information.  I understand that they'll have to upgrade to VPLEX 5.4.1 and RP 4.1.x.y at some point.  Having read through all this, I do have questions:

1) Is a VPLEX required at the third site?  Nowhere does it say it does, though nowhere does it say it doesn't.

2) MetroPoint aside for the moment, could they with RP 4.0 at sites A and B, replicate both sites production volumes (not the recovery volumes for each site) to site C and have a full backup of their data for DR?

3) So not to sound thick, but really what does MetroPoint give them versus the question above?

Thanks in advance.

K.