so, benny confirmed as being actually Benny, stuck in there.
Actually no, not in the least. The 'facts' are:
Benny was a chubby dude that fingerbanged some gal, stole her oven, did drugs with David, and got in a fight with David's sister (speaking of which, what ever happened to her or her husband?)
"Lenny" was a person with Aubrey Plaza's physical form, that was in Clockworks with David for an indeterminate amount of time, that liked music and candy, and got telefragged by Syd-in-David's-Body.
The theorizing:
This season appears to be establishing / ret-conning that the Shadow King had taken over Lenny's body (possibly even willingly) and was using that to warp David's mind at Clockworks.
Furthermore, given Farouk's dapper appearance and behavior, this season appears to be establishing that The Beast from last season was just Lenny given ultimate power - she's a psychopath.
Note that this allows them to reframe the pilot as "Lenny tried to take David's body from Syd and was killed by Syd in self-defense", rather than "Syd accidentally murdered someone".
The music box being Syd's seems to indicate she is the real revenge target - but whether that's Farouk pissed she defended David's body or Lenny pissed she took David's attention remains to be seen.
As for the ending, who knows. Too many people can swap bodies (or control of a body, in the Carys' case) to make anything obvious. I would guess Farouk's body is destroyed with Lenny driving - but who has control of any other body afterwards is unknown.