Also not fixed in 1.8 pre-release.
Still not fixed in 14w34d
You should give a little more detail on this. Maybe record this issue with a screen capture software, or take enough screenshots to show this? I know what you mean, but we could use a little more detail.
Yep. Not fixed in 14w25b.
The delay happens because when you press "Done", the client is loading any resource packs that you have selected, even the Default pack. The higher resolution the resource pack is, the longer the delay is.
I see this problem too. It's like a black line going across the horizon.
Might I also include that I also landed on the ground in the rainy parts of the biome, and I didn't hear the rain hitting the ground. I could hear other sounds though, so it's definitely off. In 13w36a, the Extreme Hills only had snow in it (from my point of view. I may have not looked that well enough, despite deeply examining it.).
One of the problems of the biome setting in the custom world settings menu still exists in 1.8.1-pre2. Set it to a certain biome, exit the menu, re-enter the menu, and it will be a different biome. I set it to DesertHills, then exited and re-entered, and it said TaigaHills.