Help with setting up WAN link using tagged VLAN

Mods: My apologies, Somehow I seem to have posted this in the wrong forum. Please move appropriately. Thank You.

Hello Everyone! Thank you for such a great resource!

I'm a little new to this game, having been tossed into the deep end before I am ready. At least I haven't drowned yet.

I am in need of some help getting a remote facility WAN link set up. The remote facility is approx 300 miles away in a very rural area. Currently, this office is set up with a 1.5M T1 internet connection. We have a full time VPN tunnel set up between the 2 offices. As you can imagine, this is terribly slow and cumbersome.

To resolve this, we have ordered a 75M connection through a provider. The home office connection will not have internet access through this connection while the remote office will. In addition, we will have one IP assigned to us by the ISP. The link uses microwave from the main office to our provider's office, then transions to fiber for the majority of the distance, then back to microwave to the remote facility. The provider has informed us that the connection will be a tagged VLAN.

I am trying to figure out how to make this work. I believe we have the equipment to support this, but I am not sure of the best way to set this up. I also understand that in order for the remote location to be able to access servers in the main office routing will be required through either a layer 3 switch or an actual router. Fortunately we have both.

So the equipment I have available to me is
Main Office: Enterasys B3 layer-3 switch and a Cisco ASA-5510.
Remote Office: Cisco 2921 router, Cisco ASA-5505 with base license and various layer 2 switches.

So my question is, how would you guys set this up? Of particular interest is how to set up the remote facility with the internet access through this link on that side.

Also complicating this issue is that I can not access the 2921 at the remote location. It's internal IP address has not been documented and I am having a hard time finding it. I went through the arp list on the 5505 and checked every IP, but none of them seem to be the 2921.

Thanks for any input,
Michael