depends on the car. may want to bring it to a car shop just in case (not likely to be a bomb)
Get your brakes tested. I do not know what a ticking sound means.
it is safe to drive slower because you could get in a car accident if you drive really fast
NO! Depends on your definition of safe?
The driver is responsible for the condition of the car and the safety of passengers. It it is not safe to drive, don't.
Depends on your definition of safe.
Yes
It is safe to drive you car for at least one mile after the check engine light comes on.
Yes
NO, not safe to do so
car smells of gas inside and out
It is safe to drive, it won't burt into flames. Your concern should be the mold that will eventually grow.
The minute that car was driven off the dealer's lot (assuming it was a dealer), the money clock starts ticking - if you decide to return the car "undriven" you are certain to incur some expense if at minimal.