Break it up and have the illusion of flowing text. There is no need to have all of it in one text box. As far as having them coexist in one box as a linked file (not placed), this does not look to be possible.
With respect to inline images, place an image and set up runaround. In indesign this is achieved using the "text wrap palette."
Frankly, there are a whole lot of reasons not to link text files. Adobe hints:
"When you update a linked text file, any editing or formatting changes
applied within InDesign are lost. Because of this risk, linked text
files are not automatically updated when the original file is edited."
In a document of any complexity, especially with multiple people involved who are not well-versed in the workflow, little changes become total train wrecks 5 pages later. Helpful features such as "auto-added pages" etc become weapons of mass destruction.