I'm going to be blunt here...
You own a truck you don't know much about and it sounds like you can't work on it on your own.
You should consider selling it and buying a plane ticket home then get in another sport car, something you are use to and move on...
I use the diamond disc, they clog up on aluminum but work good on steel and don't contaminate when tig welding... I use a needle scaler if there is heavy scale...
Until you slow down your just throwing crap on a wall and hoping it sticks... Save your money for when you really need it, that would be a game changer...