The booties are knit in one piece and seamed down the back and sole at the end. It’s an easy pattern to change the stitch pattern to your likings. Just follow the shape of the pattern to keep the stitch count.
The gauge is not tremendously important as long as you stick to small needles. One skein of yarn will allow you to make two pairs.
I have now also posted a pattern for matching mittens. You can find the pattern here in my Ravelry Store.