With many layers of paint you are bound to find more hidden rust repair / crash damage.

What do you want to do with the car? Sometimes making discrete repairs and blending in the spots could be more cost effective than a less than better overall repair / paint.

The car does have inherent value so spend $ wisely. If you put a $ 10 K body / paint repair on the car that is less than better, the cars value does not go up $ 10 K.

As for pulling the trim yourself: That is possible however if the shop reinstalls they are likely going to charge more than if they took it off in the first place as figuring out where stuff goes / tracking down missing bolts / fixing trim damage caused by the car owner leads to much more work.