Valley of Idols

Q1: Can I decide to not trigger <<Star Spring>> when I play a non-token unit there?

A1: Yes.

Q2: Similarly, if I choose to trigger <<Valley of Idols>>, does the cost need to be paid on finalization or resolution?

A2: Finalization.

Rules for Context - “they may” vs. “you may”, 383.3.a., 383.3.b.