Hi, Smiley. For the first three questions, I would recommend reading the Dream Control Training guide. It’s very helpful as far as those three. The finger through your hand feels different for everyone, some people say it feels squishy while others feel nothing at all. I think your dream characters get silent because you’re pointing out to them that they are not real, therefore have nothing to say. I would probably go silent, too, if my maker told me that I was not real. I think most dreams end up feeling like old memories, but again that really changes from person to person. My own dreams always feel the same whether lucid or not.
Hope this was all helpful!