So I've been trying to optimize and setup my own personal build system for a while now. I'm doing this because it's easier than just downloading the prebuilt ones from the download section because I'm trying learn more about networking and security.
OpenWRT has a world of possibilities and options pre/during/post compliation and on first boot and while in use. So what is important to one person, is trivial to the next.
Without drawing a line in the sand of what your requirements are, you will just end up with a bunch of "Oh this, and oh yeah that" type info to cobble together that may or may not matter to you in the end. The Wiki really is great in finding info. It's just learning what to search for start with google on what you want to do, maybe it has a technical term/name to what it is, then use the tech term in OpenWRT wiki to see if something like that is available, whatever it may be. Then go from there, search user experience and examples, then make your own.
-You need to alter .config or cat your whole config.seed into .config
-You then need "make defconfig" otherwise ( could be wrong...) the buildroot will pick up a change without sync and automatically make oldconfig ( remove your change )
-Also cat .config | grep YOUR_OPTION..... there might be an additional # not configured line there too!