Do I therefore have to invest in a tree, I want it to be paired (can apples be peared?) with a crab apple over an arch

Now hears a question - how do I know which is a boy tree and a girl tree?

When is the best planting time - spring?
I just don't want to nurture it to four foot high to find my plans for blackberry & apple crumble fall by the wayside. By the way acording to Weakest Link a dewberry is a black berry - never knew that!

Just eaten salad with home grown garlic chives - yummy and free!! don't you just love it