Not sure about the cold hardiness of Neem, but I can say that this is one of the best trees for greening deserts and arid areas. consider it an instant shade tree, 2 years and you have a shade. once established you never have to water them. people in the very dry areas here in the south west of DR. plant them in areas you only see cactus and spiny acacias growing.
of course the other benefit, is you can make homemade pest repellent. oil from the tree is used to make soap , to treat skin ailments. and as a repellent. you can even find Neem in toothpaste, supposedly whitens teeth.
The little berries I have tried, the ripe ones do not taste bad, a bit like Spanish lime, but smaller like miracle fruit.
The other tree I always recommend for the dry areas here, is Moringa. for being multipurpose.