Or, more likely, your car had previously been sold thru a "Buy Here, Pay Here" type predatory dealership. They frequently use remote-shutdown devices to remotely disable vehicles of people who don't make their monthly payments. Another option is it was a poorly installed alarm. From all accounts, the GPS trackers that are being seen have plenty of on-board battery to not need any connection to the vehicle wiring. Post more details (like pics of the circuits) and I bet someone can tell you exactly what the device actually does...
Anytime you convert AC DC there's some loss due to inefficiency. They can create DC centrally more efficiently than doing it in each and every server chassis (like your home computer does, in the power supply). This efficiency has a two-fold effect as well, since that lossy conversion results in heat as a byproduct, so the more efficient you are with getting power from generation to work, the less you spend on cooling it too.
The OP already has the online storage covered. This is regarding using HDD's for offline (not spinning) storage. Even if they're not being accessed and are physically separate from the primary storage, you still are subject to wear (spinning platters) and things like power surges.
Putting the dries back into their orignal enclosures, or perhaps an "OEM Pack" piece of foam (with anti-static bags) may be the best option. Better, consider putting the whole mess into a media-rated fire-safe.
Well, if you're going to pull a big Cat6 (or whatever) run and then crip ends on it, it doesn't matter if you're building or buying - it's not the right way to be installing the cable.
For a long run like that you should be terminating both ends into a patch panel of some sort. Mount the cable and panel securely - the solid core cable that you're probably buying isn't designed to "hang loose". I'd strongly suggest you run 2 or 4 cables at the same time. Cable is relatively cheap, labor isn't, even yours. This way when you change vendors, get another circuit, etc you'll already have teh run done. It also gives you an easy way to check if it's a cable issue or now when something stops working.
Run the cables, patch panel on each end, then factor-made stranded-core patch cables from teh panels to the endpoints.