Oh no, it wasn't the same trickster at all. According to folklore, "trickster" is like...a class of supernatural being. There are many tricksters, there isn't one Trickster. And besides, SPN's Trickster turned out not to even be a trickster at all.

If Cass hadn't told Dean about Asher and Dean found out? I think he might have left Cass. Not because he was angry but because he would have felt that he couldn't trust Cass anymore, that Cass was putting their relationship above the mission.