Sometimes with hoods there are things that have to be considered up at the top of the bands if you do different bands. But if this pattern is written for adding several rows of crochet along the edge I don't see why you couldn't just as well knit them. You could do like you say and add stitches to be worked for the bands and then sew it on, but I don't like to do the sewing if I can avoid it.
My favorite bands are knit on, I think they give a nice sturdy border. I pick up stitches along the front button band first and work it in ribbing or garter or seed stitch. I find it usually works nicely if you use 2 sizes of needle smaller for the band (sometimes 1 size smaller works) than you knit the sweater with and pick up 1, 2, 3 and skip one all up the side, absolute perfection is not required.
I then manage to pick up the same number on the button hole side. To decide where to put the buttonholes I have a very technical way of doing it. :lol: I make a mark on a sheet of paper for each stitch. After figuring out how many stitches I need for each buttonhole (often two) I use my marks to see how evenly I can space the buttonholes. I make them ___ number of stitches apart and mark the stitches that will be used for the buttonholes themselves. I usually get all the buttonholes the same number of stitches apart and adjust the placement of the top and bottom buttonholes to make everything work. I use a little math sometimes but always check it with my visual crutch. I sometimes have to make several attempts to find the set up that works best. Then when I knit the buttonhole row I use the numbers of stitches I've figured out for the placement.
The sewn on band you mention will be nice too. Make it slightly shorter than the edge of the sweater and stretch it a bit as you sew it on.