Since I am currently dealing with five translations for certain BGT-WeiDU and mods at this time, I'll put forward my experiences:
1. Pain in the ass. I don't know this project well enough to ascertain any re-wording of sentences and consistency changes to dialogue, but when you have to start asking people for one-liners every week, it feels like the translation will never get completely finished
2. Testing. I won't have a go at translators here, because I feel that they are doing an excellently, but honestly, I really don't know if the translation is correct or not. You would have to send a test version back to the translator to make sure everything looks OK (and in one case, one translator reported that he had made typos and had to correct himself!), and even then, since you only have one point of view, the relevant language community might have quirks with the way certain things are phrased. For a commercial example, Ascaron Entertainment received some appalling feedback from the French community for the absolutely dreadful translation that was made to Sacred
3. Lotsa lines. Yes, people get dispirited when they scroll down and find that it takes them 60 page downs to get to the bottom of the file. As you said, trying to divide them up between many translators is a nice idea (like the Italian translations for BGT-WeiDU at the moment). It works OK provided there is communication between the people concerned, but at the end of the day, it still needs checking and refining. When you have several thousand lines, that's a lot of checking and refining
4. Encoding issues. You have to work out how to ensure that DOS encoding (for WeiDU prompts etc.) retains all the special characters that other languages have (even your Russian, Kulyok, will need to make sure you use the code page 866 encoding - I hope you know what that is!). All in-game text will require standard ANSI encoding. And no, unicode WILL NOT WORK. Very careful attention needs to be placed on making sure that you don't accidentally save a file in the wrong encoding and screw up the entire text viewed on the screen. I had to work around all this using three dodgy notepad replacement programs in tandem. Windows XP language settings don't allow code page cross-compatibility.
Overall, I really recommend patience. Don't get excited about setting deadlines and such. Don't be pressured by the community to make the translation. Perhaps even set 30 minutes per day to do 50 lines. I wouldn't recommend barraging into it all, because you start wondering why the hell you are doing it. Hence this thread.
So that is my spiel on the issue. Good luck!