Q-in-Q tunneling with MC-LAG in juniper.

Dear Friends,

1) Is it possible to configure a Q-in-Q tunneling along with MC-LAG in juniper. If Yes what shud be the configuration and if No what is the reason?

2) Why do we use Q-in-Q tunneling is it because we can extend the VLANs because of it i.e. More than 4096 VLANS on a switch or it has some different purpose?

3) Can you also help me with the Q-inQ tunneling configuration part for the diagram I have attach if MC-LAG with Q-Q tunneling is not possible?

In my set-up we have 2 distribution switch QFX5100 private LAN connected with Cloud Chassis Access Switch(EX4300).

Please help as it is quite urgent.

Thank You Advance.