Yes, you will get about half as many uses from 500ml as from 1 liter. Remember to increase development times after half as many uses as well.(posted 9593 days ago)It's not unusual for fixer to pick up a brownish (or pinkish) tint after fixing (especially with T-grain films). Don't worry about it.
If you don't mind longer development times, using Xtol at a 1:3 dilution then discarding it yields great results, and you don't have to worry about adjusting development times to maintain consistent results.
Mike