She has Aradia’s time travelling music boxes, Gamzee had them pre-retcon, they must have found them on the meteor or something.

All ships are canon  except Johndave

For ectobiology you attempt to appearify something/someone in the past but they can’t teleport to you or they’d break their timeline so what appears before you is a bunch of goop basically has their dna/genetic makeup.

John did this for Nanna, Mom Lalonde, Bro Strider, and Grandpa Harley.  Half of this goop was used to make clones of those people which would later be sent into the past to become those people.  And the other half of the goop was used to make the kids.  Nanna and Grandpa Harley’s goop was mixed together to create baby John and Jade. While Bro’s and Mom Lalonde’s was mixed together to make Rose and Dave.

Karkat’s was a bit more complicated because trolls.

I tend to overwhelm people when I talk about Homestuck one-on-one so I usually keep it inside.

no

No, they already made the Genesis Tadpole, they just need to go get it from Echidna.

Barcodes mean that they’re clones.  

She made it

The time player doesn’t need to perform the scratch they just need to enter so the scratch construct can exist.

Not in story (not counting Mini-strife)  but in official Homestuck merch, yes.