The description for the Electric Energy Accumulators 1 has a small typo - electirc instead of electric.

For future reference:

production was at 24kW (bar was full)

This means you're producing as much power as you can.

consumption was 24kW (bar at probably 70%)

This means you're producing 70% as much power as you need.

If a furnace has no items in the input or output slot, but is processing an item, sometimes it will not show an overlay when ALT is active.

Screenshot: http://puu.sh/4h4Ya.jpg
Both furnaces are fed by inserters. The left one currently has no items in it, but is processing a piece of iron ore. The ...