I currently have nailbomb in the bridge of the ibby and a cold sweat in the neck. I wish for these to go in the Les paul. I am not sure if the nailbomb magnet is alnico or ceramic. BUT - I would like to have the cold sweat in the bridge and the nailbomb in the neck. Would I also have to have the magnets switched?
The Cold Sweat neck has an Alnico magnet and works well in the bridge. However, I would not put the Nailbomb bridge pickup (regardless of whether its an A-Bomb or a C-Bomb) in the neck position of any guitar. It will be too loud, too bassy and not balance well with the bridge pickup, especially with one that is only vintage level output. If you want to move the pickups to another guitar I recommend to use them in the designated positions.
Also, is it easy enough to get silver (Nickel?) humbucker covers as these are just the black open coil covers?
Are you asking whether the cover will fit the pickup? If the pickup has open coils and no cover the cover should fit without any problems. If the pickup already has a cover (BKP offers black covers, too) then this cover must be removed before a different cover can be fitted.
Cheers Stephan