facebook page and twitter feed - these should both start asap, and include the 'news' of the updates etc etc. Later, when the mod is released, you will actually have an audience to announce it to. future content of fbk.tw.website to include events, fanboypictures, videos of epic battles, escaping from pirates, etc.
proper website - not a forum. it doesnt need to be super amazing, it can be written in word press, saying what the game is, and how we've changed it, with a blog from the devs (content taken from here): blogs are easily searchable by google spider bots, and there are WP plug-ins that automatically repost your content to tw and fbk.
a you tube channel, with content from battles, as well as simple 'how to' videos for weapons grouping, drift fighting
not sure about this idea, but sanctions also - the names of the characters are sufficient anonymity, and it shows that there is a regulated environment here
