Keep in mind, since I have no direct experience with this product or anything like it, anything I am posting here is speculation.
I've installed quite a few radios and alarms in the past, as I used to install mobile electronics professionally. And that wiring diagram in that link looks pretty straight-forward. To me, it looks like those red and black wires, labeled power+ (power-plus) and power- (power-minus), are simply the main accessory power and ground connections for the device. Someone said that the black wire should go to the negative wire of any accessory outlet -- and yeah, if the black wire is for ground, then that should work. But ground is ground. If that black wire is meant to go to ground, then any solid chassis ground should work.
My next question would be, where did you hook the red power+ wire? Did you tap into the fuse box? If so, are you sure you tapped into an accessory-powered wire, and not a constant hot-wire? And did you tap into the protected/fused side of the fuse, or the powered side of it? Because if you tapped into the powered side, and something goes wrong with your circuit, then the fuse you tapped in to would not be a part of the circuit and would not protect against shorts -- so you would need your own fuse to your wire right where you tapped into it. And even then, there could be problems if your camera causes more current, overall, to be drawn on that circuit than what it was designed for. So, I never like to tap directly into factory fuses. On my car (2015 Civic LX Coupe), I get the accessory power from the wire feeding the cigarette lighter/power point. First of all, that circuit is meant to supply power to aftermarket accessories up to a certain amperage (since people plug GPS, radar detectors, cel phone chargers, etc. into that power point). And secondly, the wire is already protected by a factory fuse -- but to be safe, I still also always wire my own fuse right where I'm tapping power, anyway.
The spark while hooking up ground does seem a little weird, but a couple things could cause this. For one thing, if the rest of the device was already getting power (like if you hooked up the red power+ wire first and that wire was powered up), touching the black wire to ground would suddenly cause circuits in the device to be powered up and could cause a small spark if it's drawing a fair amount of current. It's best to hook up the ground first, and in this case, you would not want the power+ wire to actually be hot/powered up until you're completely done installing the device -- or at least completely done with the wiring -- and ready to test it. If the power+ wire is hot/powered up before you hook up the device's ground wire, then power may flow through the device in unexpected ways and potentially cause problems. Another thing that could cause a spark is if you tried to hook up that ground wire to something that is not actually a ground wire. Where did you try to hook up that black wire?
Next, how about that reversing lamp wire? Where did you hook that up? It seems like it is meant to hook up to the wire that powers the back-up lights when you put the transmission in reverse, but again, I'm just looking at that diagram and don't have the full instructions.
Finally, do you know whether the power+ wire is meant to go to accessory, or to ignition? In general, an ignition power wire is usually hot/powered up while cranking the engine when starting the car, but an accessory wire is not. I would not think that power-when-cranking would be necessary for this device, and the wire diagram does say "ACC" which implies accessory, but it could be something to verify in the instructions.
So, I realize that these suggestions do not fix the issues you are experiencing with your iMID screen and door locks, but these could be things to check if you try to re-install the camera system after getting your iMID and locks fixed. I would've guessed that you blew a fuse, as well, causing the iMID and door lock issues, but you said you already checked the fuses. All I could suggest there is to get a hold of a detailed fuse guide for the car to see exactly where all of the fuses are, and to see exactly which ones may affect the iMid and door locks, then double check those fuses.
Beyond all of the wiring and fuse possibilities, I would be concerned about the product itself. I've never heard of the brand, and I'm wondering if the product is defective.