Clear my doubts regarding csas portal

I had 6 subjects in class 10th , ( 5 main + 1 additional called artificial intelligence ) , do need to fill my main 5 or all 6 .

Im a dropper , do I need any additional documents?? and I have ,migration and character certificate for the year 2024-2025 (12th academic year) do I need to make new one ??? I saw that they are saying " last six months)