Yeah, when Candace first mentioned the girl and the other guy at the hotel lobby I wondered what that was about, since she didn't go back to it nor connect it with anything else. Now with the interview of 'Mich' we know why that was significant. So my impression is that 'Mich' did mention this to Candace, but at the time she decided not to mention Erika. In the interview with Mich, when he mentions Erika, Candace says something along the lines of that info being very explosive, that she had doubts about releasing it to the public, and that she preferred to let people hear directly from Mich.
It does sound like Mich told the same story from the start to Candace, except she didn't tell the whole thing to the public. She does do that by her own admission - get info and release it bit by bit 'strategically' or after she's decided it's trustworthy. 'Keep her cards close to the chest'.
My impression of the Mich guy is that he is telling the truth. On the other hand, what he's saying is 'too good to be true', so I think we should be cautious anyways.
As for Erika, my impression is that she could have been involved on several 'shady' levels without being aware that Charlie was to be murdered. She could have been tasked with being Charlie's handler, or maybe she was sincere in her relationship with him while at the same time being very much invested in the financial success of TPUSA and therefore acquiescing to all sorts of shady agendas. There's a number of possibilities there.