Under RCW 9A.52.080 (1) A person is guilty of criminal trespass in the second degree if he knowingly enters or remains unlawfully in or upon premises of another under circumstances not constituting criminal trespass in the first degree. (2) Criminal trespass in the second degree is a misdemeanor.
If you get charged with trespass you should most certainly contact an attorney to discuss your options. In the mean time, make sure your address is correctly listed on you driver's license.
You'll know if you're charged within a month or so -- you'll be sent a subpoena. You'll want to make sure to check the mail at the address the police took down. You don't want to miss a court date and have a warrant for your arrest issued!
If you are charged, you need to hire a lawyer -- especially considering your vocational goals. Ideally the charges would get dismissed so you can truthfully say on your law school and bar applications that you've never been arrested or charged with a crime. Either way, it is a simple misdemeanor, and probably won't keep you out of law school or from practicing law. I do think that, if you're charged, you'll have to let all the schools you're applying to know. Good luck!