420 and 450 are two different wattages if you didn't notice. One of them uses more power right?
1. If you've burnt down two homes you have some other serious issues going on
2. If you didn't pay, you had insurance and they certainly did if the fires were your fault
3. I don't know how they do it in florida, but I'm a landlord here in cali and in all my lease agreements the renter is responsible for all damages. Burning/blowing houses up count as damage by the way. If the fire was accidental my insurance would cover it but if they were running hash lab and blew it up, they would be responsible.
Im seriously done now. Good luck buddy, your going to need it