It's not like astral projection though. This spiritual gate allows them to enter the spirit world, while astral projection is projecting your spirit in the physical world which is where the airbending part comes in I bet.
He could only use fire unless Raava went in and "switched" his bending capabilities. He couldn't use them all until he was bound with Raava.
yes, but raava held 3 of them for him until the merge.
oh, thats right, Aiwei projected his spirit into the spirit world to meet with zaheer.
He learned them but he couldn't access them without her.
No he is definitely seen using them, it's just kinda... weak
He can't use them without her merging temporarily with him. Even so, he is always weaker than when he fully merges with her/
I actually thought about that, but if this idea was seen as op it would have been immediately shot down by the developers. It WOULD be cool if you could use a command to link with another player, being able to project to them instantly no matter how far. I think that you shouldn't be able to go REALLY far, but distance could be decided.
She didn't lose her elements, as she is seen bending post-Raava-removal.I rewatched season one and two, and in that scene I was really hoping that she'd try bending or something, but she never does. She goes straight to the tree of time and turns into the blue Korra and has a power rangers style battle with Unalac. I'm not sure if she would have been able to use the other elements or not. Raava didn't restore her bending when Amon somehow severed her connection to the other elements using physical bloodbending. I wish there was more information on this throughout the series. My guess is that if she in fact was severed from airbending, if Zahere ever lost airbending he would still be able to astral project. Not sure tho