This is indeed a common need, and many dozens of thoughtful readers have spent hundreds and hundreds of hours, literally, discussing this at length here on these forums over the years. You can access every aspect of the topic using the “Advanced Search” feature of the forum and search for: “indexing vs. importing”. The research has already been done for you – please dig in.
I recommend anything on this topic by Bill DeVille, Greg Jones (Greg_Jones) and Christopher Mayo (FROBGOBLIN). Read Christopher’s blog on the topic. Read Joe Kissell’s book on DEVONthink.