Digitrax has several PDF files available for setting up consisting on their web site (e.g., http://www.digitrax.com/ftp/zephyrmanual.pdf).
Their universal consisting feature assigns an alias to the consist (the locos have their own addresses). Of course this will vary with brand and model.
Co-owner of the proposed CT River Valley RR (HO scale) http://home.comcast.net/~docinct/CTRiverValleyRR/
The main thing to consider when determining how you're going to set up the address is, what DCC system are you using and how do you want them to sound?
What I mean by this is, do you have a DCC system that supports Advanced Consisting, and do you want the horn and bell in both models to sound off or for only the lead unit?
These models have the QSI sound decoder which supports advanced consisting that automatically turns off the bell, horn, and headlight on the rear unit, but keeps the prime mover sound active if you set them at individual addresses and then make them into a consist.
If you set both to the same address, all of the sound effects and lights will remain on, which could cause weird results such as the two bells ringing out of sequence with each other, which is not how a real train performs.
With advanced consisting, if you intend to run them back-to-back, you will be asked by your DCC system which locomotive will be the rear unit, and whether it will run in a forward or reverse direction. If you give them the same address, you'll have to set CV 29 to tell the rear unit to run in reverse if this is the way you want them to be.
Other than that, the choice is up to you.
Addresssing is up to you. If they are going to be running together all of the time, I'd give them the same address. Perhaps the same long address but different short addresses. Then run them together on the long address. Apart on the short address.
As far as them running together out of the box? You will have to try them. Every mechanism is different and most likely will need a little tweaking to run perfectly together. Run them for awhile to break them in because they will change after run-in.
Yesterday I purchased a Walthers Proto 2000 C&NW A/B unit(s) both powered and both with QSI sound. Do I give both units the same address...different addresses? Will I have to adjust speed tables or should they be compatible out of the box? Any advice you can pass along will be great.
Dave
'there's something happening here, what it is ain't exactly clear' Modeling the Hard Knox Valley Railroad in HO scale http://photos.hardknoxvalley.com/