3d painting strangeness

I use the 3d paint feature in blender(latest sculptmode windows build) and I have problems with the updates and alpha blending with uv-mapped 3d painting.

The uv mapping works just fine and it also shows up in the rendering and 3d view, but if i paint something on the map in 3d or uv-view updates of the map seem to happen randomly. Sometimes I get an instant update sometimes nothing (when rendering).

The paint brush also seems to change randomly from affecting alpha or not. How can I have the paint brush not affect the alpha value of the texture?

Jpeg is not lossless so I lose quality every time I save the map. Is it possible to save the painted texture in another (lossless) format?

I’m going to have to try this build out. And one of the first things I am going to do is see how well it works with Gimp verse.