2) There is actually two links on the sidebar, projects and translation tool, which both list all projects we have. There is Special:LanguageStats too like mentioned above, but it has some issues.
3.1) You can either do it yourself with Finnish team, or you can try organize all translators to collect list of terms. Then each language could just use at basis for their own work. You don't need to be a developer to do that. What comes to external tools, we are not aware of any suitable, nor do we have much surplus developer manpower to integrate them. If you can help us, great!
3.2) We are educating developers about i18n, but it is slow process and new developers join all the time. It really is up to you translators to raise any possible issues here to be forwarded to the developers if needed.
The quality of Google translate varies much from language to language. It is just like all the other aids, just aid to help reaching the final translation. You and I both know that there is no tool which makes perfect translations. As a translator here, you need to know what is good and what is bad, and ignore aids which are not helping you.
I hope you find that we have actually thought these issues and but considerable effort into them (message documentation, developer education, translation interface and translation aids). Maybe the issue here is that it's not immediately obvious we have done it. However, I think we have come pretty far with only one active developer (me) and two active staff members pushing and pulling translations, integrating new projects and all that kind of stuff (Siebrand, Raymond). Yet we support many projects and there is hundreds if not thousands of translators to keep happy (and I hope most of them are). Once again, all help is greatly appreciated.