-If screen shot doesn't work with the volume button then try enabling it on the power menu. I can't tell you if it does my vol down hasn't worked well in a long time . I know it works enabled in power menu though.
-Camera touch to focus is hit or miss if I remember right. Some nightlies have it, others don't. Fix one thing, another breaks, half the fun of using a nightly
-Somewhere in this thread if you search there will be multiple references to a proximity fix which should fix that problem, it does for most people anyway.