Looking around, it seems that most of the time we should be using です・ます体. FAQ questions seem to have this tendency to be 「～～のですか？」. The exception seems to be actions presented for use on the part of the user, especially in links such as ホームを見る which are almost always だ体. Does this mesh with people's experience of the Japanese web?
Yaay, FAQ's are getting translated. Since these are long and annoying, let us occaisionally post links to FAQs that we have translated for the purposes of group proofreading. For the other types of screens it will be trickier. (Over on lj_dansk it looks like they're posting FAQ answers before actually entering them, that may also be a good idead)
I'm a little concerned about our Native Speaker (1? 2?) and Actual Translator (1) resources, perhaps unnecessarily, but if anyone comes up with a good way to recruit, let me know. :)