Why did they develop a German edition ?
If you recall, Amanita had developed a German edition of Machinarium, and Jakub Dvorsky, head and founder of Amanita, had fairly recently said, "It's very difficult to find a reliable and professional publishing partner especially for an adventure game nowadays. Daedalic Entertainment is not only a very reliable and professional company but working with them has always been a pleasure. We are sure our next game Botanicula is in very good hands with them."
Do you think there will be an English one (like Lace Mamba's Machinarium) ?
I don't know for certain, but it seems pretty doubtful. Notice
here that it says that "Daedalic will be the exclusive publisher of Botanicula." So that word "exclusive" would, of course, indicate that this will be the only retail version....although
there's a version of Botanicula that was released in the Czech Republic, but that's where Amanita is from. So again, my guess is no, but I suppose it's possible.