you just gave them too much details. your 30 meters away might suggest that you hit a hard/sudden/unnecessary brake or lane change without checking blind spot.

if in future, just focus on your good/right part of story: driving is ok,everything normal, following traffic, staying in your lane, and you saw them in the mirror but can not do anything, blah blah blah.
which will be always honest and correct on your side.

for the cheap body shop, did the owner say New/OEM body parts. sounds like he would not replace your bumper (or replace with parts from junk yard). the re-shaping and re-painting will cost that 650 money. I think you may see the traces (since you know where they were) after the work done.

for dealer, I think they will replace the bumper and re-painting and re-shaping (if not replace the side). and after that, it'll be like new without trace.