I've updated the main rules doc with minor notes to clarify on your points. The rules for damaged Prisms now say: "When this happens, you lose the +1 Attribute bonus and any other benefits the Prism provides, but can still use Arthic Moves as normal."
And the "Using Work Together" section notes "However, for characters with zero or negative Trust, only the third option is viable – since the first two give no bonus. This means Working
Together is powerful but expensive until the characters can forge stronger bonds."
Thank you for your feedback!