If your base is near the big river the best place to find iron ores is around the Tower of Bats in F5.
In the future, when you’ll be more confident in combat, anyway, best way to farm steel will be looting them from dead npcs in cities like New Asagarth (in a run even 300 steel bars).
With a truncheon when you hit a npc you’ll se a white bar on top of the npc health bar, each hit reduce it, when it’s zero the npc will be knocked down.
ehm… no, it’s like a normal fight, not a one shot thing 
when the npc is knocked down equip bindings (like a weapon) and select the knocked down npc (I play on PC so idk on ps4 what button it is).
Now you have to go to your wheel of pain with the tied npc and select it, now the npc will be dispalyed in the inventory of the wheel.
You’ll have to “fuel” it with food and activating it. After a while, depending of the tier of the npc you captured, it will be transformed in a thrall.
Discovering it’s part of the game, well if you don’t enjoy to do all the work alone use: conanexiles.gamepedia.com 