A row counter keeps track of the rows you complete so you know where you are in a pattern. They all are dependent on you remembering to use them. They make some that you manually click after each row, some are electronic and you push a button. Some are barrels that go over your needles and you advance the wheel to the next number when you're done with the row. Some people use a paper and pencil, either making hash marks or writing out however many rows (1, 2, 3, etc.) and cross them off as completed. There's also beaded bracelets and some similar to stitch markers, that you move along with each row, changing the loop you're in to correspond to the row.
Basically, any method works, it's what work for YOU that's important.
As for cable needles, you can use official cable needles, a spare DPN, a chopstick, a pencil, a stitch holder - anything that will hold your stitches for that brief time. If it's a small cable, some people just knit them right off their left needle out of regular order, as that is essentially what a cable is. Again, it's whatever works for you.