I personally would do without the clay. I don't relate clay and drainage together at all. If you are planting out in your yard, then of course use what you have and maybe amend the soil with some compost/organics.

I would prune your plants back quite a bit. Most plants received by mail are very tall and thin...and probably could not support their own weight when wet. Pruning will give it a more compact shape as well as strengthen the entire plant.

If you are into tropical fruits...you should check out GardenWeb's Tropical Fruit forum.

Troys I am not sure if they are from the same family but here is a tutorial link about Cherimoya Hand Pollination that I found super helpful.
I can't wait to have one annona squamosa.
I am a newbie so I can't help you that much but at least here is the link http://www.youtube.com/watch?v=YTaBVR-YrQc

Hello there,
I just planted a nice annona reticulata this summer in July. From what I understand, they grow better in humid subtropical climates. I used a rich compost which I blended with native soil and fertilized every month. It has grown very well. I should get fruit next year. I hope your tree does well.