Revonne

That's not a question but a command

That's not entirely correct. Although the ring was in her hand, it wasn't hers originally. She took it in the Forest of Death that was in the Eastern Continent. It was further explained in the later chapters that she was guided to take treasures of the East, including one other thing that Eren took.

It's rebirth, not rebirth into the past. It's like dying and then being reborn a few years later. One can't know the future in that case.

First, the Mountain Range makes portals unable to be opened. Yelen can still open one as she's a spirit queen and spirits can still cross over even with the unstable portal. But with a human accompanying her, even she can't maintain his safety with the instability. I believe she told him about this before when he asked her about it after entering the mountain range. If he wanted, he would have to leave the mountain range with Yelen to have her make a Portal stable for a human to travel. Secondly, the portal can't directly connect to two places in the same realm. He would have to take an indirect route, going to the spirit realm first, take rest and then go to the wind tower location from there. That's a lot of time taken to leave mountain range and then taking multiple portals.

That's the thing. He's not saying it after working extremely hard and becoming stronger, he's saying it before that when all he sees is death around him. It's like if someone (Who has a good and peaceful life on earth) is suddenly tossed in hell. his first thought would be, if there's a way to return to the safe peaceful life that he had, instead of dying there. His first thought won't be, how can I survive all death flags here to make this my home. That thought can only come after becoming stronger.

Eren

Yes, but only if he attacks with it.

Thank you for the gift