[Befron]

ok, I have a couple kanji questions

I have one of those japanese kanji a day calendars: here's what one says

下　below, low. カ、ゲ
　　　　　　　　した、しも、さ（がる）、かだ（す） 、お（りる）

1) When I looked some of these up in the dictionary I found entries, but some weren't mildly related to the words below or low, I found nothing for カ and かだ（す）. Why is this

2) I looked up what this could be and found some other kanjis. They listed some things called on-readings and kun-reading, I noticed I could find kun readings, but no on readings in the dictionary, doees this relate to me previous problem?