I think the Trump Tower meeting is the closest to actual collusion by Trump and his family we'll see. I do wonder if, in their zeal to get 'dirt' on Hillary, they really realized what they were doing was collusion. This kind of thing in the business world wouldn't be unusual at all. If not, it had to have dawned on them pretty quickly as evidenced by their efforts to hide it and then lie about it.
Manafort could well have handed over polling date without Trump or the rest of his staff knowing about it.
Stone's knowledge about the data dump came from Assange, didn't it?
As much as I detest Trump, I just don't see him being an agent for Putin...at least one who recognized it.