can the police actually track you down by using your ip address or phone number!

Sure they can track you. Some digits of your IP is your provider who always has notes of the IP or IPs they give you. Otherwise one also can track from wwhich point things are being distributed. There is very simple programs for it and homepages that track it that everybody has access to. I checked it, I get my IP immediately, what browser I use and also whether I use XP or Linux etc. Nothing can be hidden and everything is detectable immediately.

Yes they can. They can track anyone with a computer down that has access to the Internet. And this I know because I had a neighbor who had the FBI find a man from his IP address that was talking to her daughter who was underage.