Our coach always tells me I'm strong off my pads, strangest thing is I never used to be able to play anything to save my life until a couple of years ago. Something just clicked.
If it's on that line I know I wont be LBW, so I play it on length as it's effectively a "free hit".
If its on my hips I just work it behind square, depending how quick/close to my body it is I will use the pace to send it either very fine (quicker bowler, just help it on it's way) right round to square (actually hit it rather than deflect it).
If it's full then a leg glance is a safe bet. Head in line, stand tall and watch it onto the face of the bat.
If it's a medium pace or a spinner then the sweep comes out to fuller balls, while anything slightly back of a length get the mow to moo treatment (my favourite shot).
The key to all of these (in answer to your first question) it to keep your head in line, be still at the point of impact and your front foot on the ground. Hope this helps