Good job investigating the thread Scooby he opened his post describing his order as a shit show without context that surely isn't positive and last time I checked.this isn't Pacific concepts support forum.
It's difficult without knowing your budget the HLG 550 would light a 4 x 4 well. Though the cheapest version is the v2 eco at 650$. You could get close to that with slightly less efficient v1 quantum boards with 2 of the 260watt v1 kits...
That 1200 watt light only puts out 257 watts and might do ok in a 2x4.
I think you could veg with it but you would be quite underpowered for flower in a 4x4.
Without seeing things under a scope it looks to be still spitting out pistils so hustl17s probably close with saying a couple weeks out yet. I personality don't flush and wouldn't more so with autos due to the shortened lifetime.
Why waste perfectly good medium? Coco is reusable through 3-4 runs before it breaks down into too small of a particle size. Buying it every run seems quite wasteful if you lack aeration toss in a couple handfuls of perlite
Just some stuff he says in the movie he's always talking about some new information or variables. Have to have seen the great lebowski I guess to get the humor in it.