Still relatively new on my ownership journey and while getting things figured out, need some help with this one.

I’ve gotten into the habit of checking the bilge pumps and high water alarms for blockages and function before I leave the boat. I have a hwa/pump in the forward/shower sump and an aft hwa/pump in the cockpit sump along the rear bulkhead. I have yet to find the midship pump - we’ll get back to that in a minute.

Was on board last weekend and all functional when I left. Was back on board yesterday after a week of heavy rain and found the cockpit and engine room pretty full of water. Was actually up to the high water float switch alarm - which was not going off and obviously the pump was not running. No appreciable water in the forward sump but no high water alarm either when I tested the float. The floats on both in the rear were free and activated. So I turned the pumps on from the bridge and they came on immediately and cleared the sumps.

After a little digging I found a wire had come loose from the aft pump, reterminated that and tested the float and all seems functional again. Can’t yet find anything loose or broken on the hw alarm.

So now the questions:
1. Easy one first. The 06 manual I found (on this forum btw so thanks for that and seems to correlate to my 03) shows the midship bilge is against the forward engine room bulkhead on the keel line. But there are fore/aft stingers there, as well as the black water tank between them. There doesn’t seem to be any access hatches either and this is the only bilge that doesn’t turn on from the bridge switch. So I’m not sure if it’s there and broken or if it doesn’t exist. Any ideas where to look for this pump?
2. Is it common for a wire to just ‘fall off’ while the boat is sitting at the dock? I suppose its more likely the bilge came on at some point and the wire cut loose then as the power lead from the boat harness seemed pretty thin (from corrosion?). Any good way to check for this sort of thing or is it all find and fix when failed?
3. There is a breaker panel on the engine room forward bulkhead that has breakers for the bilges, hw alarm, head pump, etc. (photo attached). I thought maybe the breaker had tripped but when I tried to toggle it, the rocker switch doesn’t seem to be movable at all even though it has a ‘on/off’ label. Is there a trick to moving these? Basically the left 2/3 of this panel appears to be like that - switches that look like rockers but don’t appear to move.
4. Any idea where the hw siren might be located? I suppose that could be the problem - maybe it was going off at some point and has failed? Seems like I need to get to the siren as part of the troubleshooting.
5. Anything I should be particularly concerned about or need to check since the water got to the high water alarm threshold?

Thanks in advance. Boat ownership has certainly been an adventure so far.