I don't do Spigot/Bukkit/Sponge/whatever, so not by me.
Most definitely is not this mod. It literally doesn't touch anything other than the nether portals. Your issue lies somewhere else.
I don't know what kind of list you're looking for. Haven't dealth with any permissions plugins.
This should be fixed now in v2.0.10
This is now possible on v4.2.24
There is one.
Are you on the latest version? v2.0.5 already fixed this issue.
Yes, the MIT license allows for redistribution as long the existing copyright notice in the mod's metadata is not removed.
What version? And you can probably ignore the message as it will work anyways.