Are there IE perd- and pezd- languages?

Faldage-- I know what you mean. I thought of Latin rhotacization, the -Vsum/-Vzum/-Vrum of the genitive plural. Also you see this in honos, honor. As for the -r-/-z- alternation, I had to take a look at the handbooks on this one. Brugmann reconstructed a series of fricatives s, z, S, and Z (as well as þ, and ð) for PIE, but most IEists today only have -s- (~ -z- as an allophone).

The weird thing about chaire ~ chaise is that the 'r' in kathedra yielded an 's', the opposite of the Latin direction.