Is there something against building on top of the nether bedrock, after getting through it by various means? (enderpearls, bedrock breakers) Would building a pigman farm above the nether be illegal? I just want to know before I start building there, other wise I'll have to build it in the normal nether.
Too much exploit and abuse possible, so : it's illegal, and lead to ban. Do not break nether roof, anyone found walking over the nether roof will be banned.
While it is not explicitly against the rules, if I recall, something will teleport you down if you are above the ceiling, primarily because there are some glitches that causes you to respawn above the ceiling (and therefore leave you stranded) and we got tired of having to teleport people down to safety.
You may want to apply the same code to the Deep Dark, I myself have been above it, and if not for some fortuitous mariculture gas vents I may have been stuck there.
Bedrock disables all right click actions when your cursor is on it, pearls and enderporter did not work, had to find a gap to drop down a block so the enderporter would work.
It's possible to throw the pearl into the sky and having it land almost exactly where you threw it, will count as throwing it at feet.