1. You can enter value for configure option: "Number words of category description to be shown" in Edocman Configuration -> Tab: Themes to limit number words showing.
2. If you want to change H1 tag to H2 in Categories page, you can modify layout file: root -> components -> com_edocman -> view -> categories -> tmpl -> default.php
You can make overrides layout for that file in current using template to avoid overridden in future.