Sometimes it's worth doing a phone interview, as applicants with English as a second language may just have significantly worse written skills than spoken. As long as they can communicate verbally, then it might not be that relevant. I am assuming that you're all working at the same geographic location, thus making talking way more important than email.
One test I commonly use in interviews is to ask candidates to write a function to sum up an array of values. A scary volume of them can't manage it at all.
I am Tom Williams, Lead Engineer at Dubit Limited (we're here: http://dubitplatform.com), and I'm looking for many devs. We'll look at anyone from Uni graduates to people with years of experience, the only prerequisite is you've got to be a passionate coder! You'll get much kudos for community involvement though, even more so if it's on something exceptionally cool. In return we promise to get you a cake for your birthday, and as much scooter action as you can handle.