It is beautiful, indeed - I expect mine to look even better due to some small details.
Answering your questions: The Bruce Foils (inclined daggerboards) provide vertical and lateral lift, like those of the Open 60s. The only difference is that in the Catri the foils are designed to lift up to 90% of the boat's displacement, while in the latest Open 60s they are designed to lift about 20% (Aldis Eglajs' estimate).
The ideal angle of heel is small. The best atitude for speed is with the ama sinking 10% of the total displacement, the foils supporting the remaining 90% and the mainhull skimming the surface.
The floats' volume is about 110% of the displacement aided by up to 90% lift provided by the foils in high speed, totalling 200% "flotation".
In short: it flies two hulls, but goes faster flying low.
When the mainhull flies higher, the rudder's foil is raised and stops lifting, so the mainhull automatically returns to the ideal atitude. This is (part of) the stabilization system patented by the designer.
With less wind, the speed is smaller and the float can sustain 110% of the displacement - but then it is sharing the weight with the mainhull. Conclusion: the foils' lift enable the floats to be smaller (= lighter + less windage).
