What does O'Brien say the authorities are most interested in within 1984? How does this compare with other leaders (e.g - Hitler, etc..)Like were...

I am going to refer to the second part of your
question.

To achieve this power, O'Brien focuses on two
types of torture, a mental torture and a physical torture. The mental concerns itself
with lies and anticipation. The physical combines with the mental in that O'Brien chose
the rat cage helmet for Winston. This was one of Winston's greatest fears to be around
rats. O'Brien was going to let the rats eat his face off. The anticipation of this
really messed with Winston, and the pysical experience would have been extreme pain, not
to mention that rats carry innumberable diseases that could spread in that type of
torture.

I find this type of treatment maybe harsher than
Hitler's starvation and labor camp type of treatment, although there may be many things
Hitler did that I am still not aware of. If you look at what Stalin did, he just purged
or killed many people. I think I would rather die quickly as opposed to being studied to
find my weakest points mentally and emotionally and then
tortured.

Power can be achieved many ways, but the most
effective is through fear. This is not right, it is not good, but it is what has most
quickly moved peoples in many of our history's events. I think Orwell uses this book to
teach us a lesson about the detrimental uses so we work to achieve through other means
that are productive and good for all people.