About writing back to kids in their journals... I began doing that as well several years ago as a way to encourage them to take it more seriously. It really worked! One cute story: one little girl answered the journal question then drew several lines with this note: "Mrs. Jaymie, write back here." For older kids I have been able to engage them in some dialogue about their answers and (hopefully) encourage them to continue thinking and reflecting on the question.
We use them to evaluate what the kids are learning and to keep a "record of their faith journey." It's a big hit with parents to have their kids' journals at confirmation.
Jaymie