Yes: Roots aren't meant to be damaged. They aren't even very cold-tolerant, relative to the top of the same plant, with root damage to potted stock sitting above the ground occurring at about 20 degrees F. higher temperature than the tops. Balling in burlap and bare-rooting kill most of the small roots, that is why top growth is stunted the first year after these are transplanted. The roots run the show, if something happens to the roots the top has to wait until these recover before it can carry on as before. With container stock you are supposed to be able to slip the plant out of the pot and into the ground with little root damage. However, in practice growers generate much rootbound stock, making it necessary for the serious gardener to wash these of soil and inspect the roots for defects, correct them at planting time. Most stock I look at here has signs of having been left in a small container too long. This includes container-grown broad-leaved evergreens. I seldom buy camellias form local garden centers as the two giant California growers that supply nearly all of the material offered here are very consistent about sending up terribly rootbound camellias. I have even seen 5 gallon stock with a small square of roots on top of the potting medium, in full view and indicating the plant sat in a square pot for a (too) long time when small. Rhododendrons, azaleas and other heath family shrubs are a problem because their fine, dense sod-like roots do not lend themselves to bare-rooting very much.

Encores do require and will tolerate alot more sun than the traditional azaleas that bloom but once a year. I have had mine for six years now. They get full morning sun, afternoon shade. You need to know that mine, at least, bloom far less in the spring than in the late summer/autumn season. So much less, in fact, that I added some traditional azaleas to my landscape because, to me, spring means azaleas, and the Encores weren't doing it. That being said, they more than make up for it with their late blooms that I adore. Last year, they bloomed heavily from early August until our first killing frost in late November. You can't say that about very many shrubs. I have found that mine like a cup or so of Holly Tone in the spring right after they bloom. I rather think they might like another in the fall, but I have never been able to find out how to time that. I don't want to fertilize at the wrong time and cause them to lose their bloom buds. Still, it seems logical that a late feeding might help the spring show to be better. Anyone know?

Yes you made mistakes. I have a collection of rhodies that has been praised for their health and I have never fertilized a nursery bought plant in the first couple years, at least. They have very low fertility requirements. Indeed, it could well have made them more susceptible to root rot; given that you are also planting encore azaleas, heavily marketed in the SE US, I'm going to surmise you are somewhere south of the Mason-Dixon where traditional rhodie varieties including the northeastern-bred lepidotes like PJM become difficult. You really need to state roughly where you are. Here's some good advice to newbies: if you see in your area, large, mature examples of something you are buying at a big box store or nursery, there's a good chance it will do well. If you don't, there's a good chance it won't. Consider I-95 corridor elevation under 500': If you live on the mainline of Philly, every 4th house will have an ironclad rhodie reaching to the second story windows. If you're in Richmond, VA, you are going to see a few here and there. South of that...I myself have never seen one but I know there are people down there who do collect them but those are enthusiasts willing to fuss over them. I'm not counting the Southgate/hyperythrum hybrids, which are in my opinion the only elepidote rhodies that non-specialists should be planting south of the Mason-Dixon and at low elevation. Or the special lepidotes bred to do well there, there are a couple but their name escapes me, one was bred by the Dodds.

The pH is extremely high for azaleas, and it is going to take a fair amount of work to fix the situation. To the point that the usual recommendation is to find something else to grow that isn't as picky. The soil acidifier you have should give application rates. You are aiming for something like 5.5. Sulfur, the usual acidifier, isn't nearly as forgiving as lime, which goes the other direction. So be careful about applying more than the instructions say at one time. This is going to take several years to fix, and then will require regular maintenance applications.