All knits are changed to purls and purls to knit, so if you were doing cables, you'd knit the stitches of the cable on all the rows.
If a pattern was k2, p3, k2, p3 on the wrong side, you'd have to change it tp k3, p2, k3, p2.
When you work the front of a pattern, lets say the stitches are numbered 1-50. On the wrong side, you're really working the stitches back from 50-1. In circular knitting, you're always working 1-50 since you're always working on the front of the piece.
When you do a sweater with armholes, most people stop knitting in the round up to that point, so you'd work the front and back separately back and forth to the shoulders and follow the decreases as written.