LOL your 8 fits in number 2. But your spot on. That is also why when i build by beds i water in nematodes. then i know they are there and i dont have to get a microscope. (nematodes are cheap in comparison lol) throw in some European night-crawlers, and boom, biolife.
Well when your ready to do that bed check out my
Hugel Kulture build. Finding some aged/decomposing wood can help reduce the cost of filling a bed. I mixed up my soil and threw it in there and was dropping clones in it a week later. Cost to fill bed was a couple hundred bucks. Pretty cheap. Most of the stuff was gotten from my local nursery.