I noticed a pattern with your post. You’d try one thing, then another, and then another. I was wondering, ok “now what did he use”. Entertaining. It all sounds good to me.
Before I'd fire it up, I'd clean that sticky stuff very good. That stuff might stink as it burns, and also have chemicals in it. It should mostly go up the chimney, just be safe.
I use “rem-oil”, made by Remington on my firearms that I keep in my gun cabinet. It sprays on like wd-40, it feels like it too, but its secret is Teflon. This helps the oil film last longer. On my guns, they go months at a time and still have a nice sheen on them when I clean and spray them again.
You can get it at any sporting goods store, like Dicks or Gander Mt. Maybe even Wal-Mart.
I am going to use it on my stove if I tear it way down for a super cleaning. So far all I have managed to do was cleaning out all of my ashes, and did a good Shop-Vac(Also made in Williamsport, PA). My dehumidifier in my basement runs right next to my stove. My cast iron is thick, I’m not too worried about it rusting away to nothing.