Checked "photos" on Houzz saw some cute ideas..scroll on thru painted family tree ...not all pics will apply

I'm a first time gardener and taking on an orchard no less : o I want to plant our own trees and have decided that espaliating them would be our best option. Does this look right though : 3m between rows of trees. 3m between individual trees in the rows. Can I group all the same trees next to eachother or are there any trees that should NOT be planted close to any others ? Also, we have clay soil so I will mix in gypsum with the compost and make a "doughnut" of straw around the raised base. Anything else you can think of ?

I was thinking maybe a pergola so that you can still enjoy the sun when necessary but have a small area where you can just relax with your family. What were you thinking?

I've got three established avocado trees, two are over 10 years old. This year they have suffered a big change in foliage with some rusted and what appear to be eaten or damaged leaves. It is dropping a lot of leaves too. They seemed to take a turn after winter, but they usually bounce back in late spring with the new growth. I can't seem to find any obvious small insects on the leaves but I'm basically treating it as either root rot, or maybe mites? Any advice on treating this, or are they gone? All the new leaf growth is being affected and is curling up, blackening around the edges. There has not been any significant frosts in a couple months. I'm based in Lower Hutt, so not ideal for avocado trees with the wind and winter frosts. But the trees have definitely been fairly healthy until this year.