I can't address the phosphorus, but your PH is too high to grow healthy rhododendrons/azaleas.

Why don't you read through the section on soil ph in rhodymans website for increasing the acidity...

Here is a link that might be useful: Soil PH, sulphur applications

I came across this article in my favorites this morning when looking for something else - you might find it worthwhile reading too.

Here is a link that might be useful: Changing soil acidity

The best way to grow acid loving plants is a raised bed with a good acidic soil. I recommend using a gravel bed under the raised bed to aid drainage and to keep the alkaline soil from affecting the raised bed. Also, make sure your irrigation water is not alkaline. You may need to save rain water to irrigate your azaleas. Also mulch well to keep the soil temperature cool and to conserve water. The azaleas may need partial shade depending upon the variety.

Here is a link that might be useful: How to care for rhododendrons and azaleas.