Regarding the Green 'signal' LED on each channel, these are typically post-preamp pre-everything else. Exactly where depends on the console, but they're typically pre-fader, and usually pre-mute. This can be changed on some analog consoles, and on many digital ones. In your case, they're right between the EQ and the Mute. So if you've got anything connected and sending audio, it'll show up on the meter, irrelevant of the mute/fader positions.
Of course, if the signal LED is on, with no sound coming in...then you have issues.
They come on solid green whenever a channel is unmuted, even on channels with nothing connected. They've worked correctly twice, when I first set up the console, and the first day the sound equipment was connected to its own dedicated electrical circuit. I figured it was some issue with the power. I have the console plugged into the power thingamijig in the rack (not sure if it's a power conditioner not) and turn everything off and on from there. I tried plugging the console straight into the wall and using the power switch, but it still does the same thing.