XG 115 and XG 105w to XG 210 VPN

I have 2 remote sites with the XG 115 & 105w

The head office site has the XG 210

The remote sites XG's do not require access to one another's networks

The head office XG does not require access to the remote sites networks

The remote sites XG's just require one way access to the head office XG

Task:

I need to setup the remote sites XG's to connect to the head office XG using client RDP to access the head office windows 2008R2 server

My Questions:

What VPN connection do I need to implement?

Can you provide the setup steps?

Do I need to configure the head office modem to bridge mode?

If so how do I configure the head office XG to connect to a modem in bridge mode?

Do I need port forwarding for remote users to connect to the head office server on the head office XG?

If so how do I configure the head office XG for port forwarding and finally

What RDP rules are required on the head office XG?

Thanks