I haven't attempted clothing yet, but I did buy a bunch of patterns when they were on sale for super cheap at Joanns. I have wondered about those notches too!! I am sure once you get the hang of it you will enjoy making clothes.
For marking the fabric if you are going to trace around the pattern you can get fabric pens that are washable. But to mark under a pattern and onto the fabric you can get transfer paper (looks like carbon copy paper). You put the paper between the fabric and the pattern and use a tool that looks like a mini-pizza cutter to trace over the pattern to transfer the markings onto the fabric. I don't know the names of these items off hand but I will look them up for you and post them!! I hope this was what you were asking for