All these are difficult issues that everyone has to address, but the first step is seeing that they are in fact issues.
OK. But surely you don't have a problem with relying on expert opinion and consensus of experts on any specific issue when we as average people have zero ability to know about the topic. We all have to draw the line somewhere on what we believe is true, like your 1 to 3 above, and where we don't believe them to be true. We have to trust expert consensus on specific topics that are far beyond our knowledge when making important decisions. For example, I don't ingest anything that the experts say causes cancer in mice, even though I have no idea if it is possible I'll get cancer, too.
Certainly if I want brain surgery I am going to look for someone I conclude to be an "expert." Even in recent years regarding such things as diet and covid and many other chemicals there is raging debate on safety. It's probably not useful to get too far into specific examples but when there are experts who say exactly opposite things it's not sufficient to rely on expert consensus. At those points you simply have to bring to do your best to educate yourself on the conflicting opinion and use your best individual judgment on which expert to follow.