No. Blood tests will not be effected by second hand marijuana smoke; however, other blood tests (such as hair follicle) may show marijuana in your system. This is because hair follicle tests never go back to normal (at least not for a while) even after quitting the drug, which makes you more susceptible to being contaminated.
Usually not most drug tests have a cut off of 50 ng but some are set at 15 ng if someone blows you a nose hit you could exceed 15 ng or if the room is really small
No, you should be ok. You may want to think about being around someone who smokes pot or does drugs.
No, you can't fail a blood test due to contact smoke. You don't inhale enough second hand for it to be in your bloodstream.
No, not enough THC would get in your system to cause you to fail a drug test.
You would have to inhale a lot of smoke almost like taking a shotgun before it will show up in your system. Some say it isn't possible period, but I had it happen before. I was really close to it and inhaled a lot of it. Hope this helped.