Also, Ethan is an Umbrella agent?
This is apparently the case, though I've not seen it yet.
Yes you do.
Whoever that is in the Happy Birthday tape can't be Clancy if the True Ending is a true ending. I have found no evidence whatsoever (but I haven't been able to play in daaays) that Clancy is the character in the tape. I'm not sure why people are saying it is, and I'm trying to understand where that connection came from. There's Andre, the producer, Peter, the Presenter, and Clancy, the cameraman, who you play as. Clancy escapes, his story discounted by local law enforcement.
The Beginning Hour demo begins with the "Kitchen" tape that says Operator: Male (Clancy) on June 1, 2017 at 11:40pm. Within that footage is the "Derelict House" tape which is June 1, 2017 at 10:23pm, which is simply listed as "Clancy Javis". Bad End actually connects up directly with "Happy Birthday", which happens the next day (June 2, 2017 at 1:11am).
So the Timeline is:
June 1, 2017 at 10:23pm - Derelict House (All three enter, two are captured)
June 1, 2017 at 11:40pm - Kitchen (Clancy is bound, Peter dies trying to untie him)
June 2, 2017 at 1:11am - Happy Birthday (Clancy dies)
The dude who you play in Beginning Hour does not have Clancy's tied bracelet thing.
You only see that in the very beginning, and in the pre-Midnight ending where you go out the backdoor and see the end of the Kitchen tape where Peter dies.
I believe people have said that Beginning Hour dude reuses Ethan's model and voice actor, but that's likely a cost-saving thing.
It's best to understand that True Ending takes place before Ethan comes to the house. In that time Clancy and Peter are captured. The Bakers also capture another guy, who sees Clancy's Derelict House tape (He never sees Kitchen). That guy goes free, but no one believes him because the house is cleaned and he's got LSD on him.
Mia's email is sent on July 18, 2017. Assuming he got it the day it was sent, Ethan runs into his shitty night a month after the Sewer Gators crew is murdered.
EDIT: I see Dusk Golem covered most of this with the DLC info, which I'm not privy to.