The skirt parts must be extended to the desired skirt length, which of course depends on your height. With the dress being open in front, one size fits more - adjust the stomacher, pleats and a bit of the side seams. The measurements given are not too accurate anyway - be prepared to do a lot of fitting. Once you've understood the principle of the pattern, you can even adjust it for different panier sizes and styles. The vertical lines in the pattern are on the straight of grain.
Stripe patterns are vertical.
In the 18th century, patterns often ran around the arm, but patterns running down the arm are fairly frequent. Same goes for sleeve flounces. For pleated strips and skirt flounces, the pattern runs across. For the petticoat, 10cm in front and back and 20-30 at the sides. The pattern doesn't give the hemline, so you'll have to adjust that yourself.