If they are on bus they legally dont need car seats.
Why dont you ring the school & ask about lunch? With it being 1.15 they may just assume kids can wait a bit longer and get fed when they get home, but you need to check.
As for sophia, again if you dont ring and ask you wont know. Id say you would have to double check because theyre very unlikely to have inifinte number of spaces to be taken up by everyones parents & sibblings.