To make this plan into reality, The Reluctant Farmer invited his parents to come for a visit and help out with the construction (my father-in-law was a farmer for a long time, and is quite handy with this sort of thing).
This weekend, they built us a barn!
The frame rests on heavy posts that have been sunk into the ground. These were tied together with 2x4s to ensure everything was square, and then the serious framing began. The bottom part of each wall is made with heavy 2x10 lumber that was lying around here, leftover from house construction, I suspect, which will stop anyone from kicking a hoof through the wall and will give us places to anchor eyebolts for tying halters to and such. The walls and roof are sheathed in plywood, and the roof will be shingled to match the shed (more or less). As I have always wanted a red barn, I'll be going to pick up a bucket of red paint tomorrow ... and we'll paint both barn and shed a proper barn red, with white trim.
Inside the barn (which is 18' by 14') we will have a central aisle with pens on either side: next to the shed are the pens for Sasha the cow and her calf (who will have to be stalled separately at night so that we can have Sasha's morning milk), and on the west side will be three small pens for sheep. It'll be nice to be able to pen up the sheep who are likely to have lambs, and be able to do all that lambing 'stuff' out of the wind and snow! At the far end of the center aisle will be the milking stall: Sasha's pen will have a gate that lets her into a slightly elevated area where I can sit outside the stall (protected from hooves by a sturdy fence rail, but still able to reach in and do the milking). We're still finalizing the interior layout and the best way to set up fences and gates around the outside of the barn to make getting critters in and out simple ... but I can already tell, this is going to make a major difference in our lives.
Three cheers for The Reluctant Farmer and his step-dad, who made this happen!