Yes. It'll stay good for a year or more. Do not let it sit out for more than 8 hours after thawing. Hold it it your underwear or use a hand warmer to keep it at body temp, 98 degrees.
No.Usually they watch you "do Your Thing" and the temp. Of the urine would have to be in a very close range.
Probably not, since the urine has to be body temp. They also usually watch you or have cameras so it's hard to bring in anything.
I don't matter, they will not let you take anything in the bathroom for you to pp in. And some place's will accompany you to the restroom. So don't pp in a cup and freeze it. They have ways of checking it . To many people have gotten caught for trying to pass a drug test. But good luck in your endeaver.