The Ruger rifles definitely are hard on stocks. I’ve heard and seen many issues with stocks cracking at the tang. Even the laminated stocks give problems in this area. For ultimate reliability I’d look into a synthetic stock, such as HS Precision. They aren’t very pretty, but they are way tougher than the factory wood stock.
Ammo availability will be a problem, so if you see some for sale, buy all you can get. It seems that Hornady is supporting the 375 Ruger much more than the 416.
I agree with others that say to use the factory iron sights, as they are very tough and plenty good for anything you’d do with a 416.
As for scopes, I can’t see much reason to go with anything over 6x. That will handle anything a 416 would be used for. Kind of defeats the purpose of having a quick handling DG rifle by putting some huge 30mm 2-10 scope on it IMO. Also, the 416 can be hard on scopes, especially on a lightweight rifle such as yours. That said, the Leupold 1.5-5x20 is lightweight and pretty rugged. So I’d look into something similar.