If you haven't been arrested now, you likely won't be arrested at your preliminary hearing -- unless the Magisterial District Judge decides to set a bail amount that you can't satisfy at the hearing (which can happen if a defendant acts like a jerk in court). Disorderly conduct and harassment are non-traffic summary offenses and they are written up on a Summons slip just like a traffic ticket. Arrests for these offenses are uncommon.
You are lucky you are only being charged with harassment against the police officer: if there was any physical touching, it's possible to charge you with aggravated assault against a police officer which is a felony! My advice to you is to hire counsel quickly, cooperate and put these behind you quickly before someone changes their mind and charges you with MORE. Best of luck to you.
Cary B. Hall, Esquire
Law Offices of Cary B. Hall, L.L.C.
121 East Chestnut Street, Suite 205
Souderton, PA 18964
T: (267) 663-9995
F: (215) 525-4364