Hello,

If you want to let users edit or create new blogs on the live site, you can take advantage of User contribution web part that allows users to edit content without accessing the CMS Desk. It also provides a property where you can specify alternative form which will be used, so you can customize the edit form as you need. For more information, I would like to point you to the following article: User contributions overview.

In terms of customizing the WYSIWYG editor, please go through the following article: Defining custom toolbars.

Best regards,
Michal Legen