You are trying to shape ( = queue ) the traffic. You can only shape ( queue ) in output direction, not in input direction. You can police the traffic in input ( and output ) direction. Also, depending on the platform, shaping is only supported on phy...

I would go for 2 x 6880 in the core without VSS. No VSS in the core if you can avoid it. VSS = single control plane = single point of failure. Also, one  day you will come across a non ISSU / VSS compatible upgrade. The only solution is to perform a ...

Yes the vlan tag 20 ( S-VLAN 20) will be added on top of the C-VLAN 10. So you will have double tagged frame with outer-tag 20 and inner-tag 10. MAC learning will be done on bridge-domain / vlan 20. Outgoing to R1, the inverse will happen. S-VLAN 20 ...