You didn't say where he's going exactly. Altitude makes a big difference to conditions. It depends how quickly he progresses but he won't be on the highest runs. Look at the layout of the pistes and assume perhaps one of the lower reds, at most. Probably greens and one blue, very unharsh.
I wouldn't bother with a helmet, you can't hear very well and he SHOULD be having lessons for a couple of days- you progress much faster. Skis don't tend to dump you as hard as snowboards, so risk is less.
Learning, cheapish goggles will be fine. It takes most people a couple of weeks to get out onto longer runs where undulations are hard to see in overcast conditions. But if he likes skiing he WILL be going again, it's addictive.
He won't be at 3800m in a blizzard this time. +1 to balaclava - flexible things.
Proper ski gloves are a big must, too many get hands hurt with other types. Salopettes (like a bib and brace - & goes up your back) I much prefer to trousers. You can wear a less bulky top, just unzip your jacket to cool off, and if you slide on your back they keep the snow out much much better.
Take plasters and ultra thick socks - hired boots may not fit well.
