The syllabus includes both 11th and 12th, with the relative distribution of marks approximately 40% and 60% respectively. There have been detailed answers on Quora outlining the syllabi, I believe, important chapters and all. I’m not sure if any of those are accurate, as I’ve never really done an analysis of papers, but your safe bet would be to prepare for it just like you prepared for Mains, and complement that by solving a lot of papers. I believe there are books available with sets of previous papers. That’s ideal.