Marijuana was first prohibited by the 1937 tax act. Basically you had to have a license to grow cannabis, but in order to get the license you already had to have the plants - at which point you had already commited a felony. Prior to that little was known of marijuana and people like Harry J. Anslinger who was the Drug Czar at the time vowed to get it outlawed as it was the drug of choice by the Mexican immigrants. During this period, marijuana eventually grew to something that the government wanted to keep outlawed, while discrediting people that spoke for the legalization of it and the general consumers as "stoners".
The answer to your question:
About 70-80 years.
Teenagers of any age might be addicted to weed, provided that one understands that the topic of marijuana as an addictive substance is controversial in certain circles; especially using circles. Weed is habit forming not addictive. Statistically kids 13-16 are at highest risk of exposure.
since the colonist discovered it in America
depends which weedkillers and how long has it been since they were sprayed
no it has long since been eliminated by your body
Yes. Long term use of marijuana has been shown to cause anxiety.
It has not been confirmed, just very strongly hinted at in the Playboy interview
Jimson Weed is not "made"; it is a plant native to India. Considering Lord Shiva is fabled to have smoked it along with Cannabis, it's been around a long time.
any type of weed can hurt you in the long run
Pets should be kept away from areas treated with weed killer for at least 24-48 hours to ensure their safety.
If by "lifted" you mean high, it depends on how long you have been smoking and the quality of the weed you've been smoking, if a first time smoker is smoking lets say, regular quality weed, about .3 Grams, maybe less
Weed killer can remain toxic for several days to weeks after it has been applied, depending on the specific product used. It is important to follow the instructions on the label and take precautions to avoid exposure during this time.
Weed stays fresh for a long time. You can put it in a plastic bag to keep it fresh for a long time or you can also freeze it.