Do all sanctioning bodies....

pretty sure only the WBO does it, but since Usyk has all of the belts at cruiser, he can challenge Joshua who has all of the belts minus the WBC

Yes they get ranked highly (if an envelope of money is included) so yes he can jump to Heavy and get a shot if the price is right

with usyk now having all of the belts, could he use it to jump the queues on all these HW's to get joshua/wilder? a current champ in the division below, wanting to move up, mandatory status?

cant seem to find any clear info on this even reading the regs of just the WBO for now, this seems to kind of indicate it though A classified boxer may request recognition as Mandatory Challenger in writing to the WBO on forms which contain substantially the provisions of the comply with the Application for Designation as Mandatory Contender contained on the WBO web site. Alternatively, the Committee may designate a Mandatory Challenger based on the above criteria. In either event, the Mandatory Challenger must agree to be subject to and to abide by the Regulations and to be bound to participate in and comply with the results of a purse. The World Championship Committee may deny a request for recognition based on any of the above referred criteria or because the Champion has an approved unification bout, or an approved unification tournament is scheduled, or if the Champion is contesting the Championship with a WBO Super Champion or a WBO Champion, or for other good cause. That seems to suggest that a mando can be stepped aside if the champion is fighting another wbo champion, which they would be. Theres champ in recess mando/contender status too, if I remember rightly tyson fury would immediately become no.1 contender for the belts he vacated?