I don't follow the pattern's suggested cutting layout either. I usually have less fabric than they call for, but I'm pretty good at arranging the pattern pieces so they all fit, even if there's a nap.
Sleeves are my nemesis, as is anything that comes in pairs or multiples. I hate having to sew the same thing more than once. With sleeves, I'm always sewing the wrong sleeve to the wrong armscye, or putting it in backwards or inside out. Just when I've finally got it in perfectly, I realize that I have to repeat the process all over again with the second sleeve. Ugh!
I've never tried zippers in a knit garment, since those typically pull over the head, but I found a good tutorial for invisible zippers in the July 2005 issue of Threads magazine. There's an article in the March 2010 issue about sewing with knits and it has a few tips for installing zippers. If anyone would like the gist of either of the articles, just PM me and I'll share.