Most of these alleged "issues" were covered in the various inquests, it's just that some people for their own reasons refuse or are unable to accept the facts.
The initial plan for Diana and Dodi on that fateful night was to stay at the Ritz. However, it was decided at the last minute to instead go to the former home of the Duke and Duchess of Windsor. Meaning that the assassination plot involving the "phalanx" of vehicles [motor bike, black car, white Fiat] would have had to know the destination, the intended route, the speed at which the Fayed vehicle would be travelling, and the nature of the vehicle itself (weight, mass, strength etc). Armed with this intelligence, they would have had to calculate the physics and rehearse and fine-tune the dynamics of ramming a large car travelling at speed so that it hit and bounced off the side of the Alma tunnel at the precise angle to run head-on into a support column with sufficient impact force to kill the back seat passengers. As they weren't a suicide squad the assassins would have had to ensure that they remained unscathed before, during and immediately after the high speed precision manoeuvres required to successfully complete the mission. Finally, they had to get themselves into position and do the deed.
All of this within real time of 30 minutes or so? Yeah, sure.
.