New 98 Mazda Millenia, lots of wiring ?’s

I recently bought a '98 Mazda Millenia L from a reputable used car dealership.  It only came with a valet key, and I was informed it might have keyless entry.  I've been searching for some general wiring help online, and I haven't had much success.  I'm relatively inexperienced when it comes to wiring, but I was trying to figure out if I had a keyless entry "box" behind my back seat today.  I realized there are too many wires for me to identify.  It also looks like the dealership went through hell trying to disconnect an aftermarket alarm system they could tell me nothing about.  Maybe you can help me identify anything for keyless entry, and/or how my aftermarket alarm works?  Here's a bunch of pictures:

Let's start with the back seat.  I was looking for the keyless box, but I didn't spy an antenna.  Here's what I saw:

Nothing obviously visible except these two terminals... the passenger side:

and the driver side:

Does any of that apply to keyless, or are those for my speakers?  Speaking of those, I found these wires on the roof of my trunk:

Moving onto the biggest wiring mess, the underside of the steering column.  My size 12's manage to catch a few wires most every time my foot goes down there.  Note that these pictures are taken at different angles, so they really don't hang down TOO much, but they certainly hang down:

That terminal in the back has a blue wire pulled out of it...

and there was this clear box with a blue wire in it ziptied to something (sorry, it's fuzzy):

While I was down there I snapped a shot of my mysterious aftermarket alarm (notice a couple of snipped black wires):

My brother discovered my alarm's speaker tucked in front of the fuse box:

Then I discovered that those wires were cut also.. a phillips helped remove the disconnected speaker, but the sticker on the back was too eroded to be read:

And a shot of the engine for good measure:

So what's to be made of all this?  Any idea what any of this stuff is?  Perhaps I should just start connecting bare ends together with the car running?  Perhaps a wiring diagram would help, if I could read one.  I'm hopeless.

I did some digging around, and it is a huge mess under my dash.  The clear box is indeed a shock sensor, specifically a Stinger Doubleguard Shock Sensor (by DEI).  I can see the black box tucked up underneath my dash, and it's very difficult to get to, so I wasn't able to get any valuable information from it.  Are there any other typical things I should look for in a DEI system, i.e. remote start, etc... and how can I tell what specifically has been cut to disable functionality?

Thanks for the help... this was definitely the right place to come.