I'm 19 and was pulled over for "barely touching the double yellow line on a turn"?

I'm 19 driving at 11:00 PM and had 3 cop cars follow me for ten minutes which pulled me over on a turn that had hazards on the right hand side. When they told me why they pulled me over it was because I touched the double yellow line when I went around that turn. The cop did not ask for ID or anything just told me to step out of the car. I passed his tests, blew straight 0's, and was very cooperative. When I asked for my sweatshirt they said they would get it for me, The cop asked for my permission to grab and search my sweatshirt. I gave him permission to grab and search my sweatshirt only. He then grabbed a wood case from my middle console that held weed in and an empty beer from the back seat that was covered by a blanket. I was then handcuffed and legally detained without having my rights read to me. the cop didn't even put a seat belt on me. When we got to the station they drew my blood and questioned me. They then gave me my charges for open container in a car, minor in possession of alcohol and a possession of a controlled substance. I was then able to call for a ride to get picked up from the station. After given the tickets I forced made to sign a paper and then was able to leave. Was what they did legal? And when I fight it what could be dropped?