Does warm water "open" pores?

Not according to dermatologists, but warm water improves the cleaning action.

While you're washing your hands, don't forget your mustache and beard. Lead dust will gladly settle on your hairy face.

All good precautions mentioned about hygiene. I recall most lead is ingested from hand to mouth. So hand washing is good practice.
As for indoor facilites, good maintenance of the ventilation system is critical. A minimum velocity, I don't recall the recommended minimum, at each point is obviously important, to keep fumes moving down range. SO as suggested, good practice to wash hands after every shooting session. Assume undesired stuff is all over everything. Also, don't eat paint chips.

In my experience on ranges a decent sink to wash right away is exceptionally rare. And good soap for lead removal is even less common. What I use is lead removal wipes (mine are by hygenall, but there are many brands) since I can do that immediately leaving the range and not transfer the lead to the steering wheel only to pick it up later.

After you wash your hands, rinse out your nostrils. And then blow your nose.

I guess I'm one of those old geezers with his head in the sand, the only lead contamination I'm worried about is the 100 - 200 grains coming out the end of someone's barrel.