Yes of course, they do not have to put father's name on birth certifiate if they are rapists... (check article).
Yes, they can... report police straight way and give them the description of rapists or not if they are masked... They can idenitfy the rapists thru the window... they can't see her but she can see them and pick which one and then compare their DNA...
Unfortunlately yes, rapists still get out of jail after few years prison here in European countries including Germany. Some repeat and some not... I would say that repeat the crime is rarely... Without rebahiltabion to correct their behavior, they would repeat their crimes.