I think you had better post up a photo of this cattleya and let us take a look. The rotting question really concerns me. Better to post a photo sooner than waiting. If there is something wrong with this orchid, you will need to contact the vendor and get it replaced. If it is rotting, then they (s/he) should send you a replacement.
Regarding your question about the ps-bulb under the medium: Usually this is not a good idea. Depending on how it looks, I would not leave it under the medium. I suspect that the orchid might have been repotted quickly to ship to you. It could have been done without much care for the health of the plant. (Just a guess.)
If possible, post up a photo and let us take a look.