Because I am ridiculously paranoid, I took the sweater off the needles last week and subjected it to a nice soak in Eucalan. After removing the sweater from its bath and laying it out of my blocking board, it seemed very slightly wider (35-36" around instead of 34-35") and considerably longer (16-17" long instead of 13.5"). The sweater took several days to dry (mostly because it was being covered with a towel to prevent feline-associated accidents), and as of yesterday it is about 34-35" in circumference and 15" long. Which means that my stitch gauge didn't really change with blocking, but that my row gauge got a bit bigger.
All in all, not too bad. I think the next step is to knit sleeve #2 while trying to keep my gauge loose, and see what happens. Perhaps ripping out sleeve #1 will become necessary. Then there's the Fair Isle part that I'm a little nervous about, having never done it before. But we'll cross that bridge when we get to it.
Next up, yet another new project on the needles that I'm really excited about. This is sort of a biggie and will probably take some time to finish, but I think it will be worth it. More when I get off my lazy butt and upload the pictures!