Possession and Paraphernalia Charges in Pennsylvania

My question involves criminal law for the state of: Pennsylvania

I was arrested in May 2011 for:

• Possession of Marijuana - 35 § 780-113 §§ A31
• Possession of Drug Paraphernalia - 35 § 780-113 §§ A32

The car I was driving in (as a passenger) was pulled over a few blocks down by a team of police cars and undercovers. They had allegedly witnessed me purchasing marijuana, and proceeded to search me; I admitted right away that I was in possession and showed the police where I'd put the two small bags totaling 1 gram, along with three roaches (hence drug paraphernalia).

I was taken to the police station, fingerprinted, and then informed if I'd assist as a confidential informer that no charges would be filed. I was told that I was given a while to think about it, and was never placed in a holding cell nor saw a judge. I didn't contact them about their offer (simply because I believe getting involved would harm me in the grand scheme of things over minor charges), and on the 7th June I received a summons for the preliminary hearing scheduled for the 5th July for the charges listed above.

My questions are, what should I expect at the preliminary? Formal arraignment, and if so, what kind? What should I expect to happen? I believe my declination of their offer will strike me in some form.

This is my first offense, and I'm aware of the "potential penalty" for both charges but would like a realistic insight if possible.

Thank you.

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