Take your pick. The result is the same, so Calvinism and Arminianism make no real difference. The Calvinists would say you were "never really saved". The Arminians would say you "lost your salvation". Neither is the Gospel. Prayers for your church.

No, it doesn't. 1 Corinthians 1:17 separates the Gospel from baptism. The Gospel is to believe in Jesus Christ as God who died for our sins and rose again. You cannot add any works (Romans 4:5).