How to view the top scores in Nethack

As far as I know, there's no way to remap the keys outside of a recompiling from source, or a crazy hack like using AutoHotKey to map entirely different keys on the keyboard to hjkl/yubn. Obviously that has side-effects though.

So you have a couple of options:

1. You may not have an actual numpad, but most laptops have a mode that can "convert" part of the keyboard into a numpad, by holding down the "Fn" key, or using a "Fn Lock" key to toggle it on/off.
2. Get used to hjkl/yubn, and be glad that if you ever decide to learn how to use vim in the future, you'll already have moving around with hjkl solidly ingrained into your muscle memory.

Your vision is based on the amount of light in the area. Most rooms are fully lit, so you can see the entirety of it. The same goes for most levels of the Gnomish Mines for example.

Corridors are not lit, which means you can only see one block in any direction. One exception is infravision, which is an intrinsic for dwarves, elves, gnomes, and orcs, allowing you to see infravisible (warm-blooded) monsters from afar, even in dark places.

As for the map, you recall the way things were the last time you saw them. If something happens to them but you're not around to see it, you obviously don't know of it. You will only see the change once you get within sight again.