The Downtek versions have not arrived yet, though we expect them in the next few weeks.
Yes, they should zip together as long as they are both the same length (ie. regular zipping into a regular).
The new Downtek bags have not arrived yet. When they do, they will be differentiated with a "Downtek" label in the product name.
The pad you ought to get is the Big Agnes Dual Core.
http://www.campsaver.com/dual-core-sleeping-pads
You'll want to get the regular size for the regular sleeping bag and the long for the long. The Dual Core is rated to 0 degrees just like the sleeping bag.
You could also go with the Big Agnes Insulated Air Core although it is rated to 15 degrees.
http://www.campsaver.com/insulated-air-core-sleeping-pad
The pad you ought to get is the Big Agnes Dual Core.
http://www.campsaver.com/dual-core-sleeping-pads
You'll want to get the regular size for the regular sleeping bag and the long for the long. The Dual Core is rated to 0 degrees just like the sleeping bag.
You could also go with the Big Agnes Insulated Air Core although it is rated to 15 degrees.
http://www.campsaver.com/insulated-air-core-sleeping-pad