You can damage parts by leaving the steering at full lock left or right for a long period.
It's GOING TO recirculate foam, motion tends to trap air. The only way to stop it is stop engine and let foam come out in reservoir, you have to repeat since foam in the rack cannot get out until it's in the reservoir also.
Done correctly you can install fluid with almost no aeration at all. The system is almost instantly self bleeding, the trick is to get the new fluid in there quick enough so that the pump can never run out and pull air. Once pump starts whining say when you are uncapping the second bottle of fluid to put in you have already screwed up.