How can I change the permisions for a role I have created so that users assigned to this new role can only edit content and not layout. I don't want them to be able to change skins or add any modules or delete pages just edit content. In other words they get no top menu and no admin or host functions.

This does not seem to work because you must also give the user edit permission in the page settings in order for the module editing to be active in the first place and that overrides any security settings in the module. Try this, login as host create a new role called Content Editor then create a user and assign that user to the content editor role. Now go to your home page and pick a module then edit its settings to give the content editor role edit permission, update and log out. Now login as the user you created in the content editor role, not able to edit the module you set permissions for, right? You have to set the edit permission in the page settings in order the user to beable to edit anything and setting this over rides the module permissions. So whats the point of the permission settings for the module?  

Have you tried this with DNN 4.3.1 or are you using some other version cause it don't work

in this version.