Fruit – Is 3 days too long to soak dried fruit for the fruitcake

I usually let it soak overnight, though it isn't necessary to soak that long. You should soak it till it forms a paste/gel like consistency and it would take at least 2-3 hours, though this website claims under ten minutes (time might vary depending on the batch of the seeds). You could also soak it in any juice or fruit extract as well.

Additionally, you can also use it in its raw form without soaking, the way one would use poppy/sesame seeds.

Washing fruit and vegetables in water is less an exercise in sterilisation and more a case of simply washing off any mud or debris. Soaking in still water does nothing to clean, well, anything really. Even if you sterilise the water and container, the fruit itself will still be teeming with bacteria which would be perfectly happy to multiply in stagnant water.

Simply wash the fruit/veg under a briskly running stream of water to remove any major dirt. There is unlikely to be anything terrible on fruit or vegetables in any case, assuming you have a healthy immune system.

If you really want to reduce bacterial load, the only solution is thorough cooking.