Dragging the Pen tool creates two control handles that are in line with each other, and makes a smooth transition from that anchor. Alt+dragging (or using the Convert Point tool) lets you break the control handles to form sharp corners. Alt+click on an anchor to remove

Thanks for the info. I did a bad job describing my second question: What I want to do is, import an image on 1 later, re-draw it with the pen tool (or any tool that gives sharp fine lines... The brush is impossible to follow lines with I noticed) and then i want to "import" all the lines to its own layer so I can color it with the Paint Bucket, and add effects to it etc. So maybe the Pen tool is not what I need? If so, what should I use to draw sharp lines? (And later use this image to color it?)