Seems like you're in the classic case of I want people to edit the site so I don't have to, but I don't want them to hose things. In the Html module users are set to Text mode as a default where they type, choose fonts, bold, etc. There is a button to go to the Advanced mode where they see the html and can make changes there. I would recommend getting the group of users who should be editing the content of the page together and doing a training session for them. Show them how to update things and what not to do. You'll ultimately have to trust your users in updating and if that is not possible then you'll have to do it. You can't assign tasks if you don't trust the people doing the tasks ;)