My understanding is that when Gus approached the Cartel in the flashback scene in BB S4 (which was set 20 years or so prior to BB) they rejected his meth business, killing his chemist, Max, and used Gus to transport their cocaine to the US.
I believe in present BCS time, what Nacho was picking up from Gus' truck is still cocaine and it's not until Gus sets up the lab, as we've seen the start of here, that Gus starts getting into the meth game to cut the cartel out, which is why the cartel try to get him to give them his chemist so they can profit.
The cartel already used Gus for transport, but Hector also had his own transport until that got busted (by Gus' order) so that Hector would be forced to also use Gus, giving him total distributional monopoly, which is why he's now moving forward with setting up the lab. Gus is a planner. Always playing the long game from the shadows.
Love that we get the birth of Saul! The line "it's just a name" is crushing as we know it becomes way more than a name, it becomes an entire persona. And of course the birth of Saul comes with the birth of crappy, low-budget commercials aha.
They definitely have given us Stacey's name before, but she's basically a side-character so I'll let it slide :P She and Mike were attending a grief counselling session at the Church, in case you were wondering :)
Kudos for remembering Madrigal's involvement in the laundry, however it's slightly different than how Eric remembered it, though I'm being very pedantic here and it doesn't matter too much: Gus does own the laundry but he is working with his connections at Madrigal, to help him finance his operation, ie. the construction of the lab etc. and Lydia is a part of that.