RE: VPLS model for L2VPN Framework document

Some questions:

1) Is a VPLS subscriber not allowed to send frames that are already
formatted as a "stacked VLAN"?
2) In the model where the SP only has one VPLS, and each subscriber is a
VLAN, how many VLANs can be supported?
3) What are the scaling limitations/determinants of the model where the SP
has one VPLS for all subscribers?

Thanks,
Mark