I'm not really up to that myself; I'm not particularly active here, and I'm still relatively new to ELL. However, whoever does take this on should consider a few things.
We are NOT in competition with ELU. How forcefully this point should be made, and in what form, is up for debate. Regardless, it should be clear.
We would strongly welcome more participation from the ELU community. There is currently some overlap, but it would be wonderful to have more of the regulars there stop by and offer their insights.
We may want to talk briefly about how we treat new members here, and the line between a good question that is poorly written (due to unfamiliarity with English) and a question that is simply poor. (This isn't intended as a slur against any other SE site. I mean that we should present our site's development and policies clearly, without regard for the standards on other sites.)
This is very definitely a Stack Exchange site. While its subject may be. . . non-traditional compared to the rest of the network, we are nonetheless finding our own identity within the SE framework. Some discussion of how we're getting there and how far we've come would be appropriate.
That all being said, I'm very happy that ELU has asked for this. I'd really like to see more interconnection between the sites, and a blog post dedicated to that should be good for both sites.