Very briefly: Reflex is the general weightshift 'implementation' of a lower angle of incidence in a tailplane of a conventional 3 axis aircraft, with respect to the main wing. It is just that it is achieved in the one weight-shift wing, rather than the conventional two. Given the lower angle of incidence for any given pitch angle, and incremental change in pitch will give a greater percentage change to the lower angle of incidence 'tail', giving proiportionaltely more lift, hence the nose-down pitch caused by the effective rearward moving C of P. Reflex is held in weightshift wings by trailing edge support wires, which are in turn supported by a centrally mounted post. Care must be taken to maintain sufficient reflex, as this is a critical safety feature in such wings: reduction of reflex can lead to a fatal manoeuver known as a tumble.
Washout acts much as in conventional wings, ensuring that the tips remain flying when other sections of wing are stalled. Combined with the swept-back wing design, this has the added advantage of moving the centre of lift aft in such circumstances, giving a strong restoring pitch down moment.
Billow shift is the mechanism by which roll is achieved. Without a 'floating crosstube', many wings would be so 'stiff' in roll as to be un-flyable. The use of floating crosstube effectively adds a 'servo' mechanism. This facilitates the billow shift, which in turn makes the roll control suitably light for practical use, in much the same way as servo tabs are used in conventional control design.
I hope this brief treatment helps.
PM