I am not sure about your level of expertise with electronics but this is a major, major undertaking and requires a high level of skill.
With good cooling these can handle up to 200A.
read the data sheet again especially the bit about thermal resistance.
Ultimately I need to have a very precise control of the electric power provided to a resistive heater.
And your thermal time constant for this is? Most people use PWM and a much higher voltage.
12V power supply voltage should be converted to ~1.5V.
Ok lets do some maths
Assume 100% efficiency, 12V in 1.5V out gives a step down of 8 times so assume you have a current step up of the same.
Output required 1.5V at 1000A = output power of 1.5KW.
12V supply current - 1000 / 8 = 125A
Does it not strike you that any of these figures are a bit unrealistic?