Oh, I'm so sorry, I forgot.
For that bit, leave your brush at 100% opacity, and actually change the colour you're painting with (by clicking on the foreground swatch in the toolbar) to 50% grey (128/128/128).
No, it's a pressure sensitivity setting.
See the little icons to the left and right of the "Flow" setting in the options bar? One of them controls it, I can't remember which.
I would try a Hue/Saturation layer for the water. Check the "Colorize" box, and try these values:
Hue +185
Saturation +35
Lightness +15
Then fiddle to your personal taste.
Ok, please read this: https://www.damiensymonds.net/2011/09/cropping-tutorial.html
Yes, I can help you with the chair. But of course Photoshop editing must not be done until raw processing is finished, so go ahead and do your raw processing then post the WHOLE photo for me.
I'm so sorry Jenn, I can't discuss this here, as it's covered in great depth in the Raw Class.
Please consider it: https://www.facebook.com/damien.photoshop/photos/a.183682458346830.39021.183680248347051/1313016648746733/
So, what was the upshot of this? Have you tried changing it back and forward any more times? Was it just a fluke, or your imagination, or definitely a thing?