What should I do about police harassment such as this?

example one and two dont seem too bad actually, just besides that being a case of cops being jerks lol. thats everywhere. now on example 3, you guys were cool. as long as you and ur bro werent out just strolling and stuff. if you guys were on the way to a destination then ur good, ur 19 n hes with you, they cant do anything. they were probably just bored and saw you guys as an eay target and something to do for a few seconds. Just learn your rights and state laws. if u are concerned about this, report it to the stations chief or watch commander. if they refuse to listen bring it to a judge. simple as that.