oh thank god for this site!
Hey, don't worry about a few extra picked-up stitches for a button band. Just keep the buttonhole spacing above those extra stitches, and you won't notice! Or, if it's more than a few stitches, just distribute them between the buttonholes, so they're still evenly spaced.
As far as your decrease goes, the part in quotes should give you 4 less stitches. Do they call for this series twice in the row? That would leave 38 stitches. K2tog is a single decrease, and in the quotes you are working it 4 times = 4 fewer stitches.
Hope that helps!
You're so cute with all your blushing. Hey, teen-knitting rocks! Yay ponchos!