First the minimum selling age.... well there is none (as far as i know). the 6 month is the amount of time you have to keep a reptile after recieving it, before re-selling. this is to prevent someone going into buisness buying and selling herps for profit.
As to the snakes, the bigger issue would be the cats hurting the snake if the snake escaped. Unless the cat's are really tiny, I can't see a 2 meter bredli chowing down. simple solution - escape proof cage
None of my snakes have ever reacted to my cats standing next to the cage, even batting at the glass. One time a young coastal escaped overnight, easily small enough to be taken by my cats, but they defend themselves suprisingly well!! My cat was being very wary when i found them together.. i think he may have been hit a few times hehe
It really should not be too much of an issue for you
