I have smoked every single day for months on end. and im 6ft 230 lbs. Passed a home drug test kit in 9 days. Did it once before after 2 1/2 weeks also.

it all depends on your metabolism and how much u smoke in a day.

thats the only thing I can think of in my case (one joint a day smoker). I highly doubt both my kits were defective.

I highly doubt you would be made to drop at the interview lol. your other questions are matters of opinion