You use 'along' for roads, paths, streets and so on. These are features that head in certain direction - from east to west, for example, or into or out of town, towards or away from the beach. If you are following the direction of a road, path or street , you are going along it.
'Over' means to the other side of something. For example, you can climb over a mountain if you walk up it and then down the other side. You can walk over a bridge if you cross the bridge from one side to the other.
And yes, you can also use 'over' with time - for example, 'I'm going to be working hard over the next few months' .