Questions about the specifics of choir dress of ICKSP canons

For some time now, I've been profoundly interested in the idiosyncracies of Catholic priest dress - particularly everyday (formal) and choir dress. Due to its uniqueness, in particular the dress of the Institute of Christ the King Sovereign Priest canons has piqued my interest. It is my understanding that the formal dress entails a black cassock with blue buttons and trimming + pellegrina, with a blue fascia for ALL the priests, superiors and the general (no zucchetto or pectoral though, as that would make them look too much like bishops or cardinals). Or is it just the general, and the lower-ranking canons wear theirs with no pellegrina, or completely black? Or perhaps, is the privilege of wearing hte blue-buttoned cassock in everyday situations tied to Monsignor status, such as Chaplain of His Holiness, which the Prior General happens to hold? Regarding the choir dress - it is said that it consists of a cassock, rochet, manteletta and mozzetta + biretta & distinctory. However, most available images (both photos and illustrations) also seem to include a second cape of sorts that encompasses the priest's figure even more widely and seems to be worn right under the mozzetta. While the Prior General is demonstrated to wear this part in full blue in the schematic, Gilles Wach seems to wear it black, in this photo for instance: This cape of sorts is not described anywhere (I can't find it at least). So my question is: is this part a ferraiulo? It seems to be a completely separate layer from the manteletta, which is directly below it. Whether it is indeed a ferraiulo or not, then it would seem that these canons' choir dress is the most extensive and elaborate out of all Catholic clergy, combining the manteletta with the mozzetta, and even throwing in this extra cape for good measure. But I would like to be sure what exactly it is. Thanks!