Especialy the tire rules are stupied. How can one know what weather will
be 2 days later? Cold? Hot?

I think the rule requiring they run on the same set of tires they
qualify on adds a lot of interest. I'd be OK with allowing a single
tire change after, say 20 laps.
I think there is an exception for rains. If it's like other series,
the race officials have to declare it a rain race, then it's OK to
change to rains.
On the other hand, they are running grooved tires already

Also the qualifying: The single "unordered" qualifying gave equal
chances to everybody. But now what when it's raining?

Nobody likes that. It will almost certainly change before the season
goes much farther.
Of course, the season may be effectively over already! FIA has
summed all the Michelin teams to a hearing on June 29, to answer for a
list of "Crimes".