I have two mature deciduous azaleas. This year i have encountered problems on both. Last year they were in great health and produced alot of flowers, (which i deadheaded most). This year one has not bloomed at all. The other has only bloomed about 1/10th of the plant. The Soil is acidic, but very compacted. Due to there proximity to a tree I wanted to dig by them however i was scared of damaging the roots as i think that deciduous azalea have shallow roots and am not sure of where to dig without causing damage. Also two of the main branches on both azaleas have died and i wanted to prune these. Again i was not sure how to do this, whether to take off the entire branch and how far to do it. ( Would require a saw) as i want to make clean cuts with alcohol. I will try to post photos tomorrow as this would be easier to see the problems. Main questions i would like help with:

Care questions i have outlaid blooming, pruning, and compaction.
Approximately how far out do the roots extend and depth (rough radius) .

I would be greatful for any advice anyone could give me..

Thanks for reading