Bill DID NOT BREAK BRET'S NECK!!!!! YES Bret was injured by Goldberg(a thrust kick) caused a severe concussion and over the course of a day or two(Starcade/Nitro/Thunder) possibly received up to 3 more from matches. the concussions resulted in post-concussion syndrome(and eventually a Stroke; I believe)that forced him to retire. if you are going to spew crap online, you should at least check your sources
The funny part is the "Goldberg broke his neck" line was, by far, the most credible part of the post. Obviously he has no concern for things like facts and sources.
Anyway, obviously, Vince would only trust people with the screw job plan that he knew were on his side. He knew Triple H and HBK weren't in cahoots with WCW, considering they didn't like Bret and were under contract with WWE and HBK was the one who benefitted from it. Obviously, Shane could be trusted. But let's remember a few important points.
First, he plan wasn't finalized until the day of the show. While it had been talked about before then, and guys knew it was possible, nobody knew if Vince was going to go through with it until that day. And at a time when nobody had cell phones, it wouldn't have been the easiest thing in the world for somebody to sneak off and tell Bret. Earl Hebner, for example, didn't find out until he was behind the curtain. Obviously he couldn't tell Bret during the match. Gerald Briscoe is the only other person who knew, they've said they didn't tell Pat because he was close to Bret, and I'm sure Gerald never left Vince's side after he found out.
Plus, Bret had people warning him that it could happen. Probably had people warning him that it WOULD happen. But, obviously, he wouldn't screw the WWE unless he was 100% certain it was definitely happening. And I'm not sure there was anybody he could trust that much. Obviously he wouldn't trust HBK or Triple H, or their friends, as far as he could throw them. Would he trust Gerald? Maybe, although he probably would've dismissed him like he did the guys like Vader who were warning him. Unless Gerald told Pat, and then Pat told Bret...but, again, there probably wasn't time for that. Bret has said that he didn't think it was happening because he trusted Earl Hebner, and Hebner didn't know until seconds before the match started.
So, to answer your two questions:
What if Bret found out? Well, I don't believe it was possible for Bret to find out with enough confidence that he would go out there and screw the WWE. Because nobody knew it was definitely happening until just before it happened, and those who knew that day either wouldn't tell him or didn't have the opportunity to tell him. If, somehow, Bret was aware it was definitely happening, that would've been a disaster, clearly. Who knows what would've happened.
And was Vince paranoid about Bret finding out? Probably not, for the reasons listed above. He didn't tell anybody it was definitely happening until that day, and the only people who knew definitely wouldn't have sabotaged him. I'm sure he was just focused on executing the plan.