Possession of Marijuana with Previous MIP in Other State

My question involves criminal law for the state of: Missouri

Hi,
A few weeks ago, I was walking with a few friends (we are all college freshman) late at night to go smoke a joint when a cop pulled up and got out of his car. My friend had dropped the joint that we were planning on smoking and I didn't think that I had any weed on me so when he asked if he could search us, we consented. I had a small bag with less than a gram of weed in my back pocket as well as rolling papers so I was charged with possession of marijuana and paraphernalia.

The reason I am worried is because, 1 year ago, i signed a continuance agreement in Washington State that would keep me from getting convicted with my previous Minor in Possession of Alcohol. It stated that if I stayed out of trouble with the law for 2 years my case would be dismissed.

My questions are these:
a) Did the cop have a reasonable explanation to come over and search us or were our rights of search and seizure given up when we consented?
b) Is there any way that I could get my most recent marijuana charges talked down to a point where they don't affect my previous continuance agreement?
c) Is there any way I could get my case closed so that when my continuance agreement expires in a year, the state of Washington either can't or won't find out about my legal trouble in Missouri?

Thank you so much for any help you can provide.

You never stated whether or not he articulated an explanation in the first place. You didn't state whether you and your buddies were smoking previous to this incident either. He will articulate a reasonable explanation as to why you guys warranted his attention if he has to in court.

Anything is possible when it comes to pleading down your case. However, what do you think this can go down to? Your charge is already minor. Any criminal offense has a strong potential to violate your previous agreement in WA.

Nope for number three as well. Your arrest should already be in the national database. It doesn't matter if the case is over or not. The arrest should show by now. A new SID # for the state of Missouri should be there as well. So, they will find out.