You don't say whereabouts in Texas...
The yellow leaves could be a ph problem. Camellias are said to prefer an acid soil.
I would not start cutting on a sick shrub... in my experience... that's the quickest way to finish it off...
are the plants blooming?
You won't want to prune the camellias... until the blooming is finished...
If these shrubs have been kept sheared... you may want to do a bit of thinning...
