Questions, questions (brushes, solids, etc)

Unrealed.com
Under the misc tutorials explains them in detail. Hope it helps

http://www.planetunreal.com/unrealed/tutespec.asp?show=misc

Intersecting is always better as a rule of thumb...just don't intersect too much or else nasty BSP holes can occur.
I can't quiet make out from the picture but if those are two solids overlapping that's a terrible thing. BSP hole a rama. If you don't want to intersect something then make sure you deintersect before adding it in inorder to avoid over lap.

Avoid method 2 when possible. If you later have to subtract something from the combo, it can cause real problems.

The solution is to deintersect the pillar and add it second or add the pillar as a semisolid...which can overlap into solid material just fine. NEVER let semisolids touch non-solids, however, or the BSP parsing methods for semi's will get confused by the non-solid's lack of collision. The two don't mix well. Visible non-solids can even cause problems when intersecting solid material. As a general rule of thumb, avoid using non-solids when possible. For zone portals, of course, you have no choice...but for things like intersecting flames, etc., semi's work just fine.

I have had, however, a couple of rare cases where a semi-solid sheet cluster (a four sheet tree) caused BSP problems and the solution was to cast it to non-solid. Generaly, the complexities of a BSP parser makes it a good candidate for bugs.

about the solidity:

solids: your main construction tool - most of the basic architecture in your level consists of these

semisolids: acts like a solid brush ingame, but doesn't cut up the bsp. example: say you have a substracted, solid cube. you add a small cube inside the big one, with one side of the small cube touching one side of the big cube. the side of the big cube is cut up into several poly's from where the small cube touches it - you can see this in the BSP view of the editor. now, should you change the small cube into semisolid (and rebuild for the changes to take place), the cut-up does not occur. This sounds that you should be using semisolids all the time, but there's some drawbacks with those - there can be trouble if a player touches two semisolids at the same time, and you can't substract from a semisolid brush.

non-solids: used for decorations, like torchflames, moss hanging on walls, gratings and windows. non-solids don't stop players from passing through them or shooting.

rule of thumb: solids for the basics, semisolids for more complex and decorative brushes, like revolved pillars and strange and intricate brushes made with the 2d editor.

this went kinda long-winded, but hope it helps...

yes, basically. there's just too many things that go like "you can do it this way if you don't do this and avoid this but then again you can just scrap all that and do it this way unless..." and it goes on ad infinitum. you can get some basic guidelines and instructions for certain situations but the general rules are very general - you'll just have to try things out to see what best suits what you're doing.