The international pier can handle up to seven widebodied aircraft at a time and as such I thought all the stands were the same size. As far as I'm aware though stand 54 is the only one with designated A380 markings. Both that stand and one next to it (52?) have double airbridges but like you say and extra one can be attached to the other stands if the need ever arose.
Also United have made changes to their winter timetables and as of yet BHX remains unchanged, still showing as 6 weekly, which is good news. I did notice however that MAN's new IAD service will drop to x5 weekly for the winter.