As to dimensions, that's kind of tricky. I'm looking at
Jenny's lay-out of the guest rooms. Imagining that the rooms are 10x10, and stairways 5 ft. wide, the "Residential Wing" is 70 feet long!

Is that not a bit much?
Maybe the guest rooms are more like 8 x 8? and stairways and hallways 4 feet wide? That would make the RW 54 feet long and 20 feet wide. If those dimensions (which still seem large, but then we're talking about a former Inn) work, that makes the alder courtyard roughly 20 feet from Great Hall to Kitchen. Okay, we'll go with that for working purposes unless someone can give me better numbers.
By the way, Kara, the "plan" is not how things are, but how Garstan plans to make them. Right now, the kitchen is part of the Great Hall, and is therefore roughly 10 x 16. The new kitchen looks, according to the drawing, to be roughly 20 x 16 feet. You could therefore fit 2 of the old into one of the new. I think Frodides would like that, no?
That would put the Great Hall at about 60 x 24. Wow again. Rather impressive!
Would a White Horse Inn have had a common room of such dimensions? Seems a bit much; but we can conjecture that the humble Eorl decided to enlarge the Great Hall while he had it rebuilt..... I suppose...