| Whats the best way of getting the rust off of this thing so
| that I can paint it/protect it?
You might consider having a metal shop replace it. In thin sheets of metal,
rust compromises the material's strength rather quickly. You'll want that
support structure to be as rigid and strong as you can get it if you plan on
this tool being useful.
If you believe it's salvageable, I find that a combination of abrasion and
chemistry is best.
With full ventilation and while wearing a respirator and eye protection, use
a wire wheel on your favorite high-power rotary tool to clean down to bare,
shiny metal. You may need a grinder wheel if the rust is as bad as you say.
Once you're down to bare metal, assess the thickness of the remaining steel
and see whether this is really worth your time.
When you have brushed it well, apply naval jelly (phosphoric acid in a gel
emulsion, available from any hardware store) according to the label
directions. This will remove most of the lingering rust and chemically
convert the microscopic remainder into a non-infectious form.
Immediately prime the metal with a primer specially formulated for steel and
let it dry well. Then you can apply enamel or whatever you want as a final