Are these terms going to be commonly understood by members of different styles?
No, they are not going to be commonly understood. For example, a student of chin na might have a good understanding of wrist locks, but simply being unfamiliar, may find gyaku to be a completely foreign term. This is problematic, sure, but it's also somewhat expected.
Do we need to always add an explanation to the term in every answer?
To a degree, yes, and certainly if asked. It needn't be an over-the-top explanation (i.e. gyaku does not need to be followed with a play-by-play of how the wrist is reversed), but broad strokes ("wrist lock") can often be enough.
If Asian kanji is used, does that need to be romanized and explained?
If they are used, the reader should never be expected to know Japanese to understand what is being said. As my technical writing professor used to say: when in doubt, write for the lowest common denominator.
Do we need a glossary?
We really have one already: google. Anyone confused can and should access google to make their own understanding better. Further, before we ask a question, we're expected to consult google first (to make sure the question isn't a relatively pointless and easily looked up one); why then shouldn't answerers expect to do the same?
Do we need guidelines on how to use Asain kanji in answers?
Personally, I use them only when I'm explaining something that seems to warrant it (the romanization of jujutsu vs. jiu-jitsu came up in an earlier question, so it seemed appropriate). For the most part, those characters are probably going to mean little to 90% of visitors and should probably be omitted unless a case specifically warrants it (such as romanized homonyms and the like).
When we got to the point when we start to edit and clean up the questions, what are the standards we should apply?
I've always liked the standard of italicizing romanizations (the latin-character spelling of non-latin-characterized languages) so as to differentiate them from misspellings. I suppose it may be handy, in cleaning up questions and answers for posterity to include kanji/hanzi in those cases if they're warranted and the individual is capable of posting them. They should certainly never be used to substitute latin spellings.
The same word can have very different meanings for different arts. How do we resolve this?
Many of the same techniques are called different things in different styles. Should there be a common / default style used for naming these? (i.e. use the Akido names)
Interesting... We could always take the Japanese approach of contextualizing the use of the phrase... If we're asking about a Judo technique which differs from a Shinden Fudo-ryu technique of the same name, and even if we're unsure if it does, we should probably tag the question appropriately with judo (in that case).