3) Most stable AOSP build
16.03 is the most stable Android build. The 16.06 had problems with USB for many users (building the latest version from source can also workaround these issues.
4) State of Freedreno gallium driver on the linux/gnu builds (Mesa version etc)
Not quite sure what you are after... IIRC DB410C has OpenGL ES hardware but the driver emulates enough missing OpenGL features to allow it to run a WM with a couple of simple effects and run tuxracer (although it is only playable at very low resolutions).
Extended renderer info (GLX_MESA_query_renderer):
Vendor: freedreno (0x5143)
Device: FD307 (0xffffffff)
Video memory: 10MB
Unified memory: yes
Preferred profile: core (0x1)
Max core profile version: 3.1
Max compat profile version: 3.0
Max GLES1 profile version: 1.1
Max GLES profile version: 3.0