I have used other Adobe products (Acrobat, PS, DW) for years but I know nothing, about InDesign.
I am planning a major writing project (using Scrivener and MS Word) that I will import it into InDesign. So my question is what is the best document format to use so that when I import it into InDesign the formatting (Titles, headings, block quotes, etc.) is preserved so that I don’t have to redo with InDesign?
One of the key points about InDesign, which it's easy to miss, is this: NEVER change the font or formatting of text directly (even though InDesign makes it easy). You need to imagine there is no way to do it. Then focus on learning and using Styles to do everything. In any long work you are likely to need to make changes to the text styles at some point - perhaps to use a different font, or font size, or hyphenation rule, or line spacing or... if you use styles this might be done in a few minutes.
Now, in Word, you CAN do the same but few people seem to. However, if you work in Word, with styles used everywhere, then this can come into InDesign. I don't mean that's the end of it or it's always simple, but I always take that as the basic process.