actually, the typical orchard mentality is a huge mono culture of fruit trees. or nuts i guess. the problem with the monoculture, is that the wild pollinators (if the monoculture is large
enough) have no habitat, and wont' visit your orchard. the result is that you have to import pollinators, which can mean big bucks.
a huge diverse set of fruiting tree's isn't really called an orchard, it's called a forest.
but we should remember there are different layers in a forest, and a forest interacts with it's many parts.
there should be trees to support the other trees. an example, maybe you plant aspen, but the aspen it'sself is never let to grow very tall, it's always cut down and mulched, for it's aspirin. there might also be any number of legumous trees, like mesquite. the problem with mesquite is the bugs, but if you have enough diversity, the bugs will have predators. another benefit of something like a mesquite tree is it's taproot that will harvest
water from the deep. it is also regularly cut for the benefit of the surrounding trees. not only does that mulch provide nutrients, but it helps keep the water around.
planting a lot of tree's, like you are is ok to do in rows. (imo) the real key is diversity. another key to look at though, is the water harvesting. if it's on a slope, you might want the legumous tree's at the top, this way the nitrogen that it puts off can eventually leech to your fruiting trees.
did this
answer your question? i think that you're planting a wide variety already squelches your concern. after that it's just preference.
a wind block, privacy, having the fruit tree's on the side that receives the most wind will collect airborne nutrients being blown in a storm.
there are many things like that to consider, but the biggest and most important thing is diversity. (also, diversity on the ground, so that there is a habitat for wild pollinators)
look up the study participated in by Dr. Claire Kremens of berkely. she asked the question "when
honey bee's die, can we be saved by the wild pollinators" her answer was "yes. but not if we keep planning fields as monocultures"