Yes. Purphoros's ability to make him a noncreature only works while he's on the batlefield. Anywhere else, including the stack, he's always a creature card.
No, because the Blightsteel Colossus is never a spell on the stack in this scenario. It goes directly from the hand to the battlefield. A spell, however, is a card on the stack, a copy of a card on the stack, or a copy of a spell. Therefore a spell only ever exists on the stack. The Street Artist copies spells you didn't cast, so essentially only any copy of a spell, like due to replicate, storm, Twincast, Jin-Gitaxias, Progress Tyrant, etc.
The Great Creature Token Project
Yes. Purphoros's ability to make him a noncreature only works while he's on the batlefield. Anywhere else, including the stack, he's always a creature card.
No, because the Blightsteel Colossus is never a spell on the stack in this scenario. It goes directly from the hand to the battlefield. A spell, however, is a card on the stack, a copy of a card on the stack, or a copy of a spell. Therefore a spell only ever exists on the stack. The Street Artist copies spells you didn't cast, so essentially only any copy of a spell, like due to replicate, storm, Twincast, Jin-Gitaxias, Progress Tyrant, etc.
Former Rules Advisor
"Everything's better with pirates." - Lodge
(The Gamers: Dorkness Rising)
"Any sufficiently analyzed magic is indistinguishable from science."
(Girl Genius - Fairy Tale Theater Break - Cinderella, end of volume 8)
The Great Creature Token Project