The way I check fixer life is to put a cut off end of film in the fixer when it is freshly made. I time how long it takes to clear. I fix for at least twice as long as this time. I write that time on the bottle.(posted 8580 days ago)As I reuse the fixer, I keep dropping the cut off end into a bit of fixer and time it. When it takes twice as long to fix as it did in fresh fixer, it is time for fresh fixer.
For stop, I use indicator stop and use it until it turns color, or I get tired of using the same stop. I mix my stop for film a 1/2 the recommended strength to avoid pinhoes.