brushes and painting

It's a CSS map that I"m working on, if for some reason that matters. I started the map on graph paper, did measurements for estimated timing to choke points and flanking points.  Then in hammer I put down the pathways, anywhere that people would walk, run, jump to, then I built the architecture around those pathways, one brush at a time, just like all of you recommend.  Sort of working from the ground up.

But I have a couple of what I think should be obvious questions:

1 - When joining any two brushes, at, for the sake of argument, a 90 degree angle, do you overlap and abutt the brushes, or do you just aim for point-contact on one edge?  I mean, leak management seems easier with butting one up against the other.

2 - Is there some way to set the texture paint tool to maintain a single texture while selecting faces instead of sampling them, so that I can just hover around the map and paint nodraw easily? (Probably some keystroke here, but I can't find it.)

3 - is there a way to lock a brush into position (other than vis and other groupings).

4 - The real reason for this posting: I assume, now that I have most of the architecture in place, I just go and use brushes to box off the top of each of the areas, one brush at a time, then paint nodraw or sky or something on each face.  So, do I get any better result by making a single fairly rectangualr box for each of these areas, or, should I just extend the current architecture up to a common height, and close off the top of that "cup" with a few larger brushes?  And, (I know this is noob, so save the slander, the learning curve for this stuff is a bit overwhelming given everything else on my plate)   I know about area portals and I've designed the space carefully.

5 - I'm having a problem with environment light.  It seems really dark.  I've followed the tut's and I, well, I did some of this back in q2 days, so I think I understand.  But, I mean, once the level's enclosed, will it be brighter?  Right now, it's just dark, and I"m  looking for that yellow-in-the-sun-dust-dust2 look.  My regular lights work fine.  (I've checked the light color and the brightness. It's something else. Something about height, skyboxes, something.)

SIDEBAR: Comment and curiosity: The advice here, the RABID advice on not using boxy shapes, well, I can't tell you how good that advice is.  I went through and redid the architecture one brush at a time and the, well, the irreguarity of it made a huge difference.  I have been doing well at using architectural elements to keep away from that flat plane problem but that advice was really useful. 

A couple of thoughts tho: a) even if you make areas and then rotate them, use different vertical areas of the map, and transtions between them, getting verticies lined up in hammer onto the grid without leaks is well, it's a freaking nightmare.  I mean, a couple of streets like Italy are one thing, but doing a set of interiors and rotating them, well, if you want to make an edit, you have to rotate the whole group BACK to x/y to make the edit. argh.  Am I missing something?

b)  If you watch people play, there is a maximum comfortable inclination/declination line for sighting while running, without losing suspension of disbelief, or becoming disoriented. This doesn't affect the best players.  But it affects large numbers of players, which decrease a map's popularity.  There is a maximum distance, say about five seconds, between areas of potential conflict or visual change. These things seem to be incompatible with vertical maps unless they are really big and outdoors. For example, the ramps on Dust are just about perfect, but Vertigo is too steep. The pace on Dust's ramps, the time between events or confict areas is perfect.  But if you want to have a map that has more vertical, you need a LOT bigger map to accompiish it without breaking the user's ability to visually understand the map. Or, rather you dramatically increase his disorientation and therefore increase his learning time for the map, and decrease his likelihood of trying to learn it. I think it has to do with POV and rendering. I had this problem on my map, and solved it creatively, but, it goes to the boxy advice you give here. Flat is just as bad as boxy. You can see the same problem in game designs. Unreal2 sucked because you felt you were on graph paper. Doom3 was similar.  HL2 map designs, did a great job of spatial navigation. But someting in the POV rendering I think needs to change with inclination and declination to solve this problem - perhaps narrowing POV incrementally after certain +/- z/axis boundaries. In natural Settings this isn't a problem. (This isn't my thing. I'm just trying to find a way to express it.) But our eyes, or rather, the neural denisty of our peripheral vision does this essentially.  The change would also help inform the user as to his orientation.

(Wierdness: I have a problem with heights every now and then.  Funny how playing the Rats map doesn't invoke it.  Playing maps where you're on a catwalk between skyscrapers does. Bizzare psychology.) 

This is a roundabout way, perhaps only semi lucid, of asking if anyone has seen a well done level with lots of vertical transitions, or wondering if anyone else has been looking at this problem?

Thanks for all the wisdom here.

#2: im not sure if this helps but if u open up the texture application
tool u can just right click anywhere u want the specific texture.

#5: for env lighting i had the same prolem.. I never totally fixed it
but if u increase the last color in ambient it makes everything
brighter atleast for me it did