taking a leaf out of someone's book

1. What does the first highlighted sentence mean? What does " mocking the main-house activities next door" mean here? What is "_in which ...." referring to?

2. What does the second highlighted sentence mean? Does it mean that he probably wanted to provoke the mind of the audience in the discussion?

3. Does the third highlighted sentence mean that perhaps he wanted to mock the irony of Chapmans (to somehow refer to chapmans performance at the same event)?

Context:

Invited to kick-start proceedings at a platform discussion occurring as part of a programme of sideshow events at the 2006 Frieze Art Fair in London, Francesco Bonami, senior curator at the Museum of Contemporary Art in Chicago, suggested, with a twinkle in his eye, that the medium of painting represented the pinnacle of aspiration for the contemporary artist: ‘Of course, everybody wants to be a painter!’, he declared. Whether he had some kind of vested interest, or was in fact gently mocking the main-house activities next door – in which the world’s leading galleries were vigorously engaged in persuading hordes of affluent punters to part with many of their pounds (or dollars?), predominantly for canvases it seemed – is a moot point. Perhaps he was merely relishing the prospect of provocation in a forum entitled ‘New Performativity?’ If so, he may well have been taking a leaf out of the Chapmans’ book of ironic playfulness: the collaborating artist brothers Jake and Dinos spent the entire Frieze Fair performing painting. Or perhaps that should be: performing making money from painting.Proposing that painting only retained its currency via its capacity to perform in the global art market, they opened a ‘studio’ at the fair in which they painted clients’ portraits for a cool £4,500 a throw in an installation called...