Light Environment: Remember that this light only comes from 'sky' textures. Lets say you have a box room where the ceiling is sky. If the light is pointing straight down (and its a not-very-noticeable colour, like grey), you wont notice it, since itll just light everything. If the light isnt set properly and it's facing upwards in any way (i think you need a negative pitch, 0 being flat, -90 being straight down, i THINK), then it wont be see at all. Also make sure the entity itself is somewhere in the map, doesnt matter where, it just cant be outside. Tinker with it a bit, make sure the flags aren't doing anything stupid (like the STARTS ON one

).
'too many lightstyles' is very bad. It messes with your compile and can do some pretty whack stuff. It tells you exactly where this is happening in the compile log, so go find that coordinate and try to figure it out. I think it even goes so far as to be a cause of the alloc_block:full error.
'-nodynbounce' means simply No Dynamic Bounce. The default for bounces is 1, i believe. So every light shines from its origin, hits whatever, then bounces once more. If you want to light up areas a lot more 'naturally', you can up the bounces (Max uses 10 sometimes even), but it WILL light up your shadows significantly. I use bounce 2. What nodynbounce does though, is that any dynamic light simply doesnt bounce. If you make a spotlight that strobes, it'll strobe and loook pretty hot, but the light wont be noticeable on the nearby surfaces (which can look cool, but isnt totally necessary, and can really up your lightdata). Its an easy fix for that error or for high lightdatas, and frankly isnt noticeable.
Light Textures: You can make your own light.rad from scratch if you want. Just make a .txt, rename it to lights.rad, and put in what you want. It is NOT affected whatsoever by client's own rad files, because they dont even have any. Its only for *YOUR* compiler, and it determines how the lights come out. When Max and i were doing hundreds of test compiles with Nexus, he had a much different rad file than mine, and its very, very surprising how much lighting can affect a map.
So yeah, every machine will see the same end result. And no, not every texture is in there, you have to add in whatever you want. If your rad already has a lot of texture names in there, you might find a few in-game that you dont want (so just delete those names), and definitely a few that you'll want to add or tinker with. If you add new wads or custom textures or whatever, just verify if they're in there, and add them in if you need to.
WADS: You can create your own wad if you'd like, absolutely. Just remember that people will need the same wad, and hence will have to download it. No worries, simply means you'll have to include a .res file with the package you make available (they are REALLY EASY to make, just check any of the .res' in the ns/maps/ folder to see what i mean. they just list the files required and their paths, like the minimaps).
Another option is to have custom textures zipped into the bsp itself. Its a command option, that doesnt always seem to work, but does sometimes

. Maybe im doing it wrong.
With Nexus, i just used hl, ns, and ns2 textures. Ive had a few complaints that, with such a crazy new map, i should've used a custom set. I think for my next version, i'll simply 'find/replace' a few of the more noticeably veil-esque textures with sexy custom ones, and then have those included in the bsp. But its your choice.
If its one of your first maps (and you're not planning on taking over a year to make your masterpiece, like me

) its probably worth sticking to the basics. All that extra time on custom stuff means nothing if the map itself isnt fun or doesnt get played. There are some really quality textures in the NS set, just try to use them in ways people havn't seen yet, and hence wont recognize. It does sound like you know what you're doing with Wally and all, so heck, custom it up if you want to

.
As for the commands, the biggies are:
-sv_cheats 1 (this also starts a round, letting you test runtimes using the in-game timer)
-developer 1 (this shows all the dev info. You're now a dev. Try having it on and loading a map)
-numents (needs dev 1, tells you the number of runtime entities in the map. Recommended is below 200, but the limit in the guidelines is under 300. Affects the stability of the map, especially with larger servers or excessive turret farming, etc)
-r_speeds 1 (with dev 1 on, you'll see a constant update of the current r_speeds at the top of the screen. Great for determining where you need to optimize. I have this bound to Home and End, on and off.)
-gl_wireframe 2 (bind this to a key, like Insert or something, then Delete as gl_wireframe 0. This shows whats being drawn from wherever you are, so you often see things way around corners and whatnot. Also shows how r_speeds are actually found. Helps with the placement of Hints)
-noclip (lets you fly through walls, a good option when you have weldables a distance away from their target, etc)
-givepoints (give you res)
-bigdig (needs cheats, but everything insta-builds, so if you start a round on a testmap, you can tech to PGs in about 3 seconds and have pgs up anywhere you want, very quickly)
-spawnhive (spawns a hive in a random hive loc)
-setgamma 1.0 or 1.5 etc (useful for determining what you want you env_gamma set at)
**** LINKS
The entire list of commands for compiling, and many other things about compiling, can be found
hereA stupidly large list of errors and their possible solutions can be found
here.
A decent list of tutorials can be found
here.
If you want to learn about Hints but want to skip ahead to the best way of doing them, all you need is the
tutorial on pyramid hints.
/needs another drink