I am probably going to be trolled for this, but is training your calves in anyway helpful for squats or deadlifts or any benefits at all?
It won’t hurt. Train it like you would for any other small muscle group. Having big strong calves as a base could help give you a bit more stability.
Probably a waste of time unless you have really rinky dinky legs. Spend the time on your hamstrings instead.
Can help with ankle strength/stability.
Not likely to do much, my calf strength doubled and I added 2" to them and nothing happened to my lifts. If you are a huge dude you might be able to bounce off of your calves. I agree they could help add ankle stability but something to also keep in mind is hammering away at the calves hard can also tighten/shorten them decreasing dorsiflexion so it is harder to maintain good form in the squat or deadlift. Having said all of that I do believe that a powerlifter should spend some time at some point training pretty much every muscle they have so it is at least decent. Improving the soleus can also help with circulation which is good for health.