Riginslinger, there's a fair summary about the mercury thing on Wikipedia, under the heading for the particular mercury compound involved.
I totally support continuous statistical checking to see whether anything is having a side-effect. The human body is a pretty complex bit of machinery and can break down in a whole bunch of strange ways, and no reasonable testing beforehand is going to catch the fractions-of-a-percent cases that get revealed over use in millions of people - it just ain't possible.
The problem is twofold. Firstly there's people's ability to assess of risk - what's the chances of *failing* to vaccinate causing damage (by allowing infection) versus the chances of vaccination itself causing damage? This actually happened to me and my sisters. When I was born, there was an MMR-like scare going on about whooping cough vaccine. My mum point-blank insisted that me and my sister mustn't be vaccinated, so my dad went along with it. We both subsequently caught it whilst young - I was 3, but she was only 18 months, not far outside the zone where 1 in 500 babies dies. She had to be taken to hospital and put on a ventilator for a week; if they hadn't, she would have been one of those statistics. My dad said he basically went through hell then, having known that the scare was a load of bull but having gone along with my mum's scare-story belief to avoid arguments.
And secondly there's people's ability to assess sources of information. It worries me (frankly it scares me) that you're lumping all those unrelated things together. I guess that isn't how *you* think, but how you think other people think? "Someone who's part of a large organisation is telling me this, therefore I shouldn't trust them because this might be part of a global conspiracy." It certainly doesn't help though that newspapers gratuitously misreport stories about scientific and medical issues, nor that politicians (John Gummer, famously) try to spin the reports.