Does water hydrate our nails, which I assume would be a good thing, or does it damage them and hence contact should be kept to a minimum?
Nails absorb water - with time. So it is probably a good idea to not soak them in water for a long time before you play guitar. But I imagine washing up hands for what is typically a short time is fine - it has been fine for me.
But the other thing to keep in mind is that the level of water content in the nails varies with ambient relative humidity. This may account for at least some of people's different experiences with nails and guitar-playing. According to this recent article
, the dependence is linear up to about 70-75% relative humidity; then the rate of absorption increases after that:
You do not have the required permissions to view the files attached to this post.