OMG! The pics are huge! sorry if you have dial-up! Some of my message disappeared also. My concerns are with the gray colored growth over the bark areas and the spots on the bottom of the leaves.

You have lichens on your stems - not a problem in itself, it's not damaging but can sometimes indicate a plant weakened by other reasons.

Your 'other reason' seems to be a somewhat advanced infestation of azalea lace bug.

Here is a link that might be useful: U of Georgia - Lace Bug

More about Lace Bugs:

They are a problem on some varieties when they are planted in the sun. Spraying is seldom a satisfactory solution. Moving the plants into the shade is the best solution. There are other plants that will do well in the sun without the Lace Bug problem.

Whitish specks on the upper surface of leaves and dark spots varnish-like on the bottom are symptoms of Rhododendron Lace Bugs, Stephanitis rhododendri, and Azalea Lace Bugs, Stephanitis pyrioides, small insects with transparent wings on under-surface of leaves.

This insect hatches early in spring as the new foliage begins to mature and its numbers may build to damaging levels with successive generations. Lace bugs reach their peak in late summer and do their worst in sunny, exposed sites.

Spiders are important predators of lace bugs and since they shy away from sunny, hot places, plant your azaleas where there is some shade.

Insecticidal soap, horticultural oil, or a systemic insecticide may spare your azaleas the damage if applied in spring when the first hatchlings are noticed. Care must be taken to spray the lower surfaces of the leaves where the lace bugs live.

Moving a plant to an area with more shade may alleviate the problem.

Lace bugs are more prevalent on certain varieties. The following azalea cultivars have resistance to azalea lace bug: ôDawn,ô ôPink Star,ô ôEreka,ô ôCavalier,ô ôPink Fancy,ô ôDram,ô ôSeigei,ô ôMacrantha,ô ôSalmon Pink,ô ôElsie Lee,ô ôRed Wing,ô Sunglowô and ôMarilee.ô