If you truly hadn't smoked for months prior then you should be fine by the 18th. No worries.
no.
There is no magic way to "clear your system" of marijuana. As long as you don't use again before the test, you'll probably be okay.
Periods come and go, I wouldn't worry to much :)
You can be sued and your car repossessed.
Yes you could be, or you might not be.
You may have lost a lot of weight
a week
If you havent had your period in 7 months you probably need to go to the doctor, that is not normal.
No
Yes, but you might be pregnant again.
Go to doctor
That's the most likely explanation.