SAMM - the size all depends upon the tension you get. In my case, I got a tension of 5 stitches to the inch, and my finished sweater with the buttons sewn on ended up at 19". (Here's hoping it fits Cameron in the fall, otherwise, I guess it goes to charity).
Zip - I had seen your BSJ in the KAL posts, and it was lovely! (one of the ones that inspired me to make mine! thank you)! Yes, I think that these buttons rock, and set off the finished sweater. I didn't specifically go looking for the stars, but the lady at the sewing store took me to the "novelty" button section and there they were - they jumped right out at me.
As for the shoulder seam, well I just did the best that I could. Tried to do an invisible seam, but it's kind of unusual with garter stitch. At the cuff, which is garter to garter, I just kind of picked up the top loops, and it didn't turn out too too badly (the stripes actually matched! ), but the next part, where it was garter to sideways-garter it wasn't as nice. I guess that it's practice. I was too lazy to do the i-cord, but next time I will maybe do that one. I was just too anxious to get the whole thing done...[SIZE=1]I have a few more projects to finish SIGH.[/SIZE]
Loved this knit. Apart from having to check the counts every so often, it really is dead easy when you get going. LOVE garter stitch.