Short answers, pulled from the story.
The Minor Reformed Church of Poland began on the 22nd of January 1556 when Piotr of Goniądz spoke against the doctrine of the Trinity at a synod in Secemin. This event marked the start of the faction that would later separate from Calvinist leaders.
The main cultural centers were located in Pińczów and Raków where the Racovian Academy operated from 1602 until its closure in 1638. Over one thousand students received training at this institution which became a major intellectual hub for non-trinitarian thought across Europe.
The Sejm expelled the Socinians from the country on the 20th of July 1658 following the Deluge wars during which Protestant Sweden invaded Poland. The Brethren were viewed as Swedish collaborators because they refused to participate in military service like other citizens.
Members rejected capital punishment traditional Christian doctrines such as Hell or the Trinity and declined to serve in political office entirely. They advocated for the separation of church and state while teaching the equality and brotherhood of all people without social privileges based on religious affiliation.
Isaac Newton collected many books from the Racovian Academy and was well informed about developments in Poland after the community emigrated to England East Prussia and the Netherlands. John Biddle translated works by Przypkowski and others into English while Andrzej Wiszowaty contributed ideas about rational religion that reached English thinkers.