1. Enable them: CP -> Portal & Islands -> Column Layout, additional settings can be found in CP -> Portal & Islands -> Portal
2. The display is fluid for HTML5 display for a wide array of browsers (such as market leaders cellphones and tablets). If you try to enforce widths it'll no longer be fluid based on browser size and could result in mobile pages no longer being mobile capable as the size can easily break the viewport.
3. common.css holds a lot of default information for the forum, you can offset the options through the forum styles you have installed (and introduce new entries with the "Extra CSS" area), however the fonts and font sizes are set to industry standards for display for the wide array of browsers, some fonts just don't exist on some systems.
4. The Forum help is handled through the faq language file.
5. Sounds like a permission issue, copy permissions from a forum that works correctly then customize as needed.
