Adtran Netvanta 3205 router and VLAN tagging

I have a customer that was given 2 Adtran Netvanta 3205's from their carrier to truncate a T1 connection between 2 of their offices.

The T1 WAN connection is working and we have some connectivity between the routers (via the WAN network which is a /30 as a ppp interface).

In configuring the main Ethernet interface (Eth 0/1) to use 802.1q encapsulation and configuring sub-interfaces, I'm trying to confirm that:

interface eth 0/1.11
 vlan-id 11
 ip address 10.1.1.231 255.255.0.0
 no shutdown

means that this particular sub-interface is assigned a VLAN of 11 and is being tagged.

For further acknowledgement, does an additional sub-interface configured as:

interface eth 0/1.25
 vlan-id 25 native
 ip address 10.25.1.53 255.255.255.0
 no shutdown

mean this is the default VLAN of 25 and is NOT being tagged?

As well, do I have to include or do anything with the PPP/T1 interface as far as VLAN tagging (similar to above) to get traffice to flow through to the other side?

I need to be able to pass other tagged VLAN's between and through each side for both data and voice.

I've also been trying to find a configuration manual for this unit, but can't seem to find that either.