You pose many good questions; I wish I could help answer them, but I keep my vivs very simple (I don't even make backgrounds).
If you can't find what you are looking for through keyword searching, it might be helpful (and pleasantly time-consuming) simply to browse build threads. There are lots of little details that can be gleaned in passing, details that are nearly impossible to find if you look for them. (This browsing advice goes for all aspects of the hobby, actually; if you want to know, e.g. how many tincs can dance on the head of a pin, just read everything everyone's said here about tincs and enjoy the feeling of your mind expanding.