Regarding liability, maybe this will explain why the tenants liability is unlimited.
If you or one of your guests reverse your truck and accidentally knock down a wall, the roof falls in and the property is destroyed? Who is liable?
Yes it was an accident, but it’s not the landlord’s responsibility, it’s your responsibility.
There is no responsibility on the landlord to insure against your liability, and if he had, his insurance company would come after you.
The big question for you is how much damage the landlord is claiming? Is it worth him pursuing legal action?