Choosing the right forum can definitely be tricky! While bbPress can be customized it can be a lot of work! I would suggest looking for another forum plugin or question and answer plugin that will meet your needs. If you’re really just looking for a Q&A format one of these other options might be a quicker solution for you!

In regard to the text area being small, when you are editing the page check on the column to the right for a metabox called “Page Attributes” and see if the theme allows you to select a Template option (not all themes have them). If it does, you’ll want to select the one that would be either full-page width or no columns.

Hope this helps,
Kevin