Are foreigners with kids on work visa in Poland eligible for the "Family 500 PLN" benefit money?

the article on the Najwyższy Czas was completely based on hearsay additionally

I don't think they'll increase VAT. It's much more likely that they'll introduce the cadastral tax and remove PIT transfers to local governments, to be honest. They could then blame local governments for high taxes.

It would be very difficult to introduce the property tax (podatek castralny) based on the value of the property, as first every property in Poland would have to be valued. In the villages (where PiS is well supported) people who exist on the minimum pensions may find that 10% tax on the value of their properties is beyond their means and PiS would soon lose votes.

Perhaps not, because PiS don't actually control that many local governments. It would probably hurt wealthier gminas more, because they're the ones likely to have nice things like swimming pools to pay for. A poor rural gmina would only really have to fund schools and not much else, and even then, they'd get away with only funding primary schools. Those poor gminas could also be subsidised in some way by central government, while forcing those in wealthier areas to pay more.

Unfortunately, it isn`t. You probably meant another benefit - tax reduction in your yearly income statement.

My apologies, you are right. Benefit payable only until the child is 18.