His not telling Claire that Jamie was alive is one of the reasons that I really dislike Frank. I don't know if he actually found them all in the C18th, but he did prepare Brianna for the eventuality, making her generally a bit more competent and self sufficient. He's just such a racist, misogynistic, adulterous git - although, I suppose, he is as much a man of his time as Jamie is of his in many respects.
Yes, the mad women do actually dress up and they try to dress like Claire in real life, too, with all their tartan frocks, arm warmers and odd blouses. Add that to the fact that they do stupid stuff like get stickers for their car that say things like "mo nighean donn", trousers that have sassenach on them and jewellery like Claire's wedding ring (not to mention their houses being full of tartan) and it's not a pretty picture of Outlander fans.
I don't understand it at all, to be honest, what are thry trying to achieve. BUT, as long as they aren't hurting anyone, there's no harm in it. I think Craig Na Dunn in just about the only character that I could impersonate - it's just about the right size for me