My reading on the codex is that through continual rebuilding the Necron systems eventually break down at which point they can't be rebuilt, so self destruction ensues.
Point 1: One could argue that over the millenia the stolen artifacts broke down or became disabled without a power source and their GPS\recall ability is inoperable. Also, who is to say that everything that was made came with the ability to be recalled, 30 million years ago (or however long), they were the masters of the universe, why would they need to recall something if it shouldn't disappear in the first place???
Point 2: As for capturing a vehicle, one could argue that you're shooting a big gun at a vehicle and disabling onboard systems in the process. I seriously doubt that the Necrons no matter how intelligent or forward thinking would build in more than double redundancy on any particular system. Any repairs made by the orcs would most likely bypass the systems that were inoperable.
As for the Pariahs, I'm glad I don't own any of those guys, but you can really see the ability for the Necrons to expand their army line ... 10 years from now with the next codex. Also, did anyone else see the pirate necron (can't recall name) that tricked the Tomb World into letting him leave? I wanna field that guy! C'Tan did get neutered, but in the same breath, it makes the Necrons that much more powerful because they subdued gods. Can't think of anyone else that's done that... more because I don't know all the fluff lol.
The background story of the Necrons did change a lot, but at the same time it's a lot more engaging and I feel there is enough information to actually write books about them now. I would certainly enjoy reading them if it happens.