“What would your best advice be on where cannabis should be stored while on the drive home from the store, since the law in N.B. doesn't stipulate an area? i.e. trunk, backseat, glove compartment, etc ”

It is your choice as to where to store it, when transporting it from the store to home, provided it is not accessible to minors. However, given that consumption in a vehicle is against the law, you may want to store it in a way to be sure there could be no confusion around that.