Brigid from MangaBlog took a few minutes at NYCC to talk to Kurt Hassler, the head of Yen, to get some more information out of him in regards to their upcoming release of Yotsuba&!
First off, volume 6 will be coming out in September, and Amy Forsythe will be the one translating the manga -- she originally worked on some of the earlier volumes of the series, so she's familiar with it and won't have to worry about developing voices for the characters.
The rights for the previous volumes will be reverting back to the Japanese company, at which point, Yen will have them. In the meantime, though, they're in the middle of negotiating with ADV to acquire their translation materials, so that they can simply reprint the volumes without much delay -- much like how FUNimation has done with all the series it has acquired from Geneon and ADV.
And for all you Yen+ subscribers, the series won't be appearing in the magazine, I'm sorry to say. Which is a shame, because for those who are just getting into manga and have picked up Yen+, they're missing out on one of the bigger titles. That is, of course, provided Yen Press doesn't pimp the hell out of it in other venues.