You can mask off faces which can help in some cases with overspray, but it's probably more useful in something like weight paint than texture paint. I'd certainly like to see the cavity masking and things like that though. Even just having a lasso tool in the image editor would be really convenient. Masking example: Click…
Ideally I'd like to have them in a menu I can pick from, like the menu you can already use to select what mode you want, but bound to a key so it appears around the mouse pointer rather than being attached to the window header.
Very cool stuff @MACHIN3 - these tools look like a breath of fresh air really ! If I understand the GIFs correctly it seems like you are going for something allowing for non-linear, semi-non-destructive editing of curvature and fillets ? If so ... well, that's pretty damn great :)