As far as the StackExchange system is concerned, your site is already permanent. I hope that helps relieve some of your concerns. :)
As far as things users can do to help, there's so much!
- Check meta regularly: The moderators (and really gung-ho users) will post promotion ideas/events/opportunities in meta, so checking it regularly means you'll get to participate in expanding the site's audience and/or keeping its scope clear and defined.
- Use the site, all the time: If you find yourself reaching to click on the WordReference forums (or some other outlet; I just always used the WR forums, ha), then STOP! and ask here instead! Even if you question is closed, even if it's voted down, doesn't matter. Asking it here gives this site that much more of a chance of showing up in Google search results. The next person who has those questions may very well land here instead!
- Tell everyone about this site: I'm not saying you should spam your entire contacts list; that's ridiculous! However, letting your university's Spanish department know, or sending a link of a really cool question/answer to a friend who also speaks Spanish, or submitting a question from this site to the Spanish-language version of Hacker News are all small things that can help a site like ours grow.
There's tons more that "lurker" users can do, but these are good jumping-off points. I can't stress this part enough: if you're not using this site yourself, then it is failing. The strongest advocates are the ones using this site every time they need it; in doing so, you help make the Internet that much better, which is Stack Exchange's ultimate goal. :D