Well, the Romans did paint their statues. We only see them as white now because all the paint has flaked off over the years. They also painted the temples and other public buildings. The white toga virillis was de rigur, and the only exceptions were magistrates who wore the purple bordered toga praetexta and triumphators/censors who wore the purple toga picta (as in my icon). Minor boys also wore the toga praetexta.

The sacrifice of the bull was modeled on the annual festival of Magna Mater. But it would have taken place outside and the people bathing in blood would have been the Galii, the castrated priests of Magna Mater. If Atia wanted to seek the patronage of a goddess, she'd have been much more likely to ask it from Bona Dea, and that would have involved her drinking wine and kissing a snake.