Circular needles just about replace the "desire" to use a straight set of needles (or even just one). When you use straight needles, you are ALWAYS AT RISK of losing one of them while you work on your project. Sorry. Dump the straights and start to gather the circular needles. On a specific project, ask a pro about the LENGTH of the circular needle is best and appropriate. Excess lengthh, honestly, never hurts, but too short CAN. You really can never make an adult sweater on a 12 inch long - you ALWAYS need long sizes. And it doesn't hurt to have a set or two of end-of-needle rubber protectors.
Next part of your question - ALWAYS read all instructions, first - then simply work line-by-line (NOT more than one line of your directions! This can often be confusing for all knitters.). When you get a little experience on this part of directions, you will KNOW when there !right be either an error in the printed directions, OR you may be in a position of your project, to knit a different way "of your own" decision.
Happy, restful, and successful knitting!!