@tjsecondtry, no idea. Maybe it's slightly more reliable than not doing them? It's definitely one our "nod and smile" cultural/practical moments. With our past travels and my involvement in student exchange as an alum (albeit, of a summer program, albeit, it was Japan so lots to have moments with!) and volunteer, it's at least been natural for me for a while! Funny story - my area once had a student from Denmark who spoke English completely fluently and with no accent whatsoever. NONE. She told me she got funny looks when paying for things with change at the beginning when she was getting used to our coins, one of which doesn't actually show the amount on it, like "What's wrong with this girl?! She's too old to have trouble counting change!" This has given me a whole new understanding of how she must have felt!
@Cbhav1, we brought the bank letters we'd gotten for the application plus newer bank statements but weren't asked for any of it. Otherwise I'm pretty sure we just need what you listed in 2. No photos needed at that point. All we got asked was basic stuff like had we committed crimes I think, had our family situation changed, etc. It was pretty casual.