These codes are criminal codes that you are referencing and you should talk to a criminal lawyer about this. Unless there is a stay away order you have the right to be in a public space near the plaintiff. You also have the right to gather evidence if it is appropriately done. Still, use your best judgment -- since you have a child in common you both need to respect each other and respect each other's privacy and boundaries.
Some information/evidence will be weighed less than other information and this is where a family law attorney can really help you.