Well you can't really use the name of a restaurant chain as your title. English to Japanese isn't my area of expertise, as although I'm fairly fluent, I'm not a native Japanese speaker, but for the king part I think you'd be better off simply using 王 (ou). As for the dumpling part, it really depends what you mean by dumpling, because it's a very broad type of food with variants all over the world. Ideally, you should ask a native speaker to get a completely natural-sounding title.
For the format, horizontal and vertical are both fine - go with what works best aesthetically wherever you plan on using it.
