Well team files are supported, but you can't really seperate the scenes or some like that, because there too many cross references. You can export team files and let somebody work with them and then reimport them. Problem is that conflicts can arise here if the team file has also changed some of the actions you changed.
Elseif is noted, there will be a lot of things overhauled in the future, the action system will get a better display as planned. Don't how it will be in the end.
The editor on scheduled to be rewritten with SDL and OpenGL without wxWidgets. That bundle is much more stable than wxWidgets. Native Linux won't happen as far I see it, even though we can build it, it's unsupportable. Linux Player is already hard enough.
4) is an often wished for feature, can't make any promises to that.
5) is noted on my list.
6) Yeah, but there is not really much to make the amount of work needed smaller. I planned some with drag and drop, don't know if that's really faster.
7) grouping is planned. But there is no possibility that we sort them at runtime, that may get you into undesirable side effects.
8) multi select is planned. You wanna see them as Lua or what ? I haven't really figured out yet, what would the best possibility to make the action parts display better.
I hate python and you will never get as much performance with that as with C++