USFM Book Formatting & Conversion

I am working on publishing a set of 70 books through RAB which have been designed in InDesign. I’m very familiar with CSS, HTML, and InDesign styles, and fairly comfortable with USFM. I want to create a future-proof workflow where books can easily be exported from InDesign to RAB when book updates are made. Making a js script for InDesign which converts all paragraph & character styles to USFM is one way forward, but that probably won’t work for tables & images. Another option is exporting from InDesign to HTML, and then converting to USFM. However, I can’t find a good overview of all USFM styles for RAB Books (not Scripture), which addresses how to deal with table borders, images, chapters, page numbers, to what degree it supports html or markdown, etc.
Also, when HTML or ePUB files are imported in RAB and presumably converted to USFM, it would be really helpful to see and modify those files so I can understand the formatting rules RAB uses.