1. We can do that as it is, but it doesn't seem to change much. If you want a biome changed just submit a modreq asking for it and what you want it to be.
/modreq Please change plot # to jungle biome!
2. This has been suggested and I'm considering it for mods+ to be able to change it, just wondering how we'll make sure it's changed back.
3. I believe donators should be able to (or will be able to) if you can't, let me know what exactly you can't use in a reply because I need to change that so you can. Also for regulars, I need to make another group, which I didn't think was possible, but now I know it is. Just give me time!
4. We can't, sadly. It deals with the plugins plot database which we don't have permission to mess with.
MCG uses a custom plugin that isn't plotme at all, we didn't think plotme was stable enough. But the same thing, it doesn't support renaming plots.