I think Colonialism is more of a neologism for 'imperialism' since the US empire has a pretty different form from the old European empires. In US Parlance it seems to refer to a wealth pump moving resources from the undernourished colonies to a corpulent administrative center. Cultural artefacts could be an example, though of course this doesn't refer to physical artefacts that the original owners lose. It's a bit weird to me as well, though I can see how stealing a cultural artefact to put in a museum and copying a hairstyle could feel similar to someone living with inherited trauma.

Oh, no; it's absolutely part of it. Cultural appropriation involves the dominant culture taking practices (including things like clothing, music, dance, etc, especially if it's part of a religious practice) of a colonized or marginalized culture, removing them from their cultural context, and using them for their own purposes.

That's absolutely subjugating the identity of the colonized: it takes these parts of their identity and says "these are not yours; like everything else, they are ours, and we can do with them as we please."