Here is a zone 3 vendor. They have a huge selection of nuts, trees, shurbs, berries, etc.
http://www.sln.potsdam.ny.us/
For general information on plant (height, yield, bloom time, harvest time, etc), check out these guys.
http://www.onegreenworld.com//product_info.php?cPath=4_107&products_id=1411
You mention citrus. Here is a few zone 6 citrus (bitter orange and thomasville citrange). With a little micro climate you might be able to take grow it in zone 4 or not
http://mckenzie-farms.com/photo.htm
As for water/earth works. Just do the usual terrace/keyline/swale/hugelkultur/imprinting depending on your terrain.
If you are worried about guilds, just do the usually 9 layer thing Nut/fruit tree/tall shurb/berries/groundcover/herbs/vine/ self seeding vegetables.
A good vine for you is artic/hardy kiwi.
Iterations are fine, we don't have to be perfect
My 2nd Location:Florida HardinessZone:10 AHS:10 GDD:8500 Rainfall:2in/mth winter, 8in/mth summer, Soil:Sand pH8 Flat