what do the #'s and .'s mean mean when rendering with yafray

eg: #…#…#…###…

also, is there a way to find out a percentage done?

it’s a progress bar. percentage might come sooner or later, but at that point this isn’t a major issue (the version number sais it’ early pre-alpha - for that, it’s really good).

Previously the '#" part meant one scanline, now it means 10 blocks of 64x64 pixels (a screen area as you can see rendered when using the plugin), so if you render a picture of say 640x512, then it will print ((640/64) * (512/64)) / 10, or 8 times a “#”
The dots are only printed when you have the cache option enabled and use anti-aliasing, it means yafray has to do brute force sampling instead of using the cache, which only happens during anti-aliasing.