If rust is basically Fe3O4-nH20, would it possible to strip it of water with conc. sulphuric acid? Would the result be magnetite?

Also, after the top procedure, if I use carbon to react with the product, would it yield iron?

 

 

Not exactly.

If rust is basically Fe3O4-nH20, would it possible to strip it of water with conc. sulphuric acid? Would the result be magnetite?

Concentrated sulphuric acid reacts with the oxide to give more water and leave iron sulfate, FeSO4 or Fe2(SO4)3.

 

In fact, sulphuric acid will create rust on perfectly clean steel (link for more info) - so it does the opposite from what you hope to achieve.

Also, after the top procedure, if I use carbon to react with the product, would it yield iron?

Carbon can indeed react in a redox type reaction with iron oxide to give pig iron and CO2... that's how blast furnaces work.

The reaction temperature is typically around 1200 deg C (see wikipedia for more info).