Using the spell storm step, does it need to be a straight line of travel or can you change direction if you still have distance left for the spell.
Its straight line.
What you’re not taking into account is the casting time. Its one standard action, and in that action, the entire effect of the spell takes place. You perform one action, and in that cast a spell which “Storm Steps” you the distance you want to go. You can’t interrupt that action to do other things (which you couldn’t anyway, because this is your ONE standard action).
You select a single point either in your line of sight, or you specify a direction and range. You then teleport that distance, and thats the entire action.
Due to the nature of the spell, I would say you would have to travel in a straight line. Lighting doesn’t normally turn corners after all.
Your DM might have a different opinion, as the Rules As Written doesn’t specify that it must be a straight line, but my common sense rules say you would have to use a straight line.
I’d say logically yes, but since the spell doesn’t specifically state that, it’s the DM’s call.