You only need to purchase the parts that I have listed as "required". The other guys question was regarding a part that can be reused.
The absorber (which you need) is a different part from the crash bar.
Yes. The 15-17 crash bar is the same for 18-20
If you have to get it painted anyways you might as well spend the extra money on a new cover and diffuser from ford so you don't have to worry about getting the bumper repaired.
Just finished up swapping a 18+ Rear Bumper on my 2017 Gt so I figured I would gather up all the information needed incase someone else would like to do so. Originally I had just cut my stock diffuser to fit my Roush active exhaust but I was never fond of how it looked nor did I like the look of...