How much brake fluid depends on how efficient you are at keeping air out of the system. Last Fall, Eric951 and I must have went through two liters of fluid doing mine before I discovered the bleeder valve wasn't seated properly and was shooting air in as we struggled to get it out at the same time.
If you have the telltale ATF leaks near the boots then its a good chance that your steering rack itself is going south. The process to pull it is a bit time consuming but not that difficult. Its definitely a DIY job, fortunately. Check out
www.griffiths.com for rebuilding yours.