Seems you already got the answer for the 2nd question, so ill answer the first.
DoM wrote:
•The size of a shooting window cannot be a small crack; you need to be able to see all of the head.
Q: Is a 1x1x1 PHX Cube sized gap between two props considered a crack? My gaps are usually about 1.5 of those, so in reality its a 1.5x1.5x1.5 block(dont exsist) space. If you don't know how big that is, please spawn it in game before answering.
I do not know what size it is in PHX/Construction props, but you should know how big a head is by looking at it. You could get a friend to help you to see if you can see the Whole head or not. Just use common sence