More features for the obsidian rank are always welcome. Especially because the emerald and obsidian rank are very alike. These gadgets, however, should not be abusable in any way, which is why I have my doubts about some of your suggestions.
Whilst the lobbies may look better during day, evening or night time, this also has a bunch of cons. As implied above, reading signs, finding your way to the boards, finding your friends and other normal activities would be hardened, especially if night time is selected. Giving all obsidian ranked players access to commands like /teleport, /gamerule, /summon et cetera would also be abused to an unimaginable extent -- it's basically giving /op to anyone with a certain rank.
Some sort of teleportation gadget (maybe a bow?) is something I'd love to see added, whether it is for the emerald or obsidian rank. It's not very original, but I don't see why this should not be a new gadget. One of the problems that could come with this is getting stuck in a wall or floor, as
@jollow250 said, but I'm sure our developers will come up with a solution for that.