Have they said who will pay for damages on a drone crash or to the
package should it release too early?

No, but I suppose that these things will be covered.

As we now, everywhere all expenses are actually paid by customers, being
included in the price of the service.

What I cannot imagine very well are thousands of drones flying over our
heads with all kind of bricks and maybe even exchanging their loads in the
air.

Considering the rapidly increasing number of mid-air near misses with
commercial flights, I don't see any real -=city=- future for them.
Supposedly limited to under 400', they've been up in landing paths at
2,000'.

There's good and also evil uses for them. If wanted, current maximum
payload is enough to wipe out a city block. OTOH search and rescue,
catastrophe assessment, etc are possible uses too.