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…
Well dont think so - just the usual turn off the modifier for the time being. But it would be trivial to write a little operator which toggles all the modifers on the selected object or something like that.
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.