All is possible. The most elegant approach is to create a userform to drive the document. Start by looking at
http://www.gmayor.com/Userform.htm and for a more in depth explanation, see
http://gregmaxey.com/Create_and_employ_a_UserForm.htm
Long texts can be inserted from separate documents or from building blocks according to selections, even hard coded in the macro - see
http://www.gmayor.com/SelectFile.htm
There is no character limit with formatted autocorrect. You can insert many pages of text and graphics with autocorrect, but I wouldn't use it for this task.