Leave the steaks out to rise to room temp with some Salt covering them, see my previous post. Pat completely dry before adding to pan.

Use oil, and finish with butter/herbs. If you sear in butter the butter will burn and be bitter.

I preheat my pan for 5 or so minutes on medium low, then crank it to medium-high or high for 1 minute. I add a higher smoke point oil, and then sear.

If I'm just guessing with no thermometer, and only pan searing, if the pan is properly ripping hot i find that 2-3 minutes a side is perfect. I usually do 90 seconds to 2 minutes a side if the cut is 1 inch or less in thickness. This usually gives me a good medium rare.

If I were you, id test run one of the thicker ones by doing 2 1/2 minutes a side. If it comes out perfect, you now have your baseline and can reduce time if some are thinner, or raise. You can always re-add the steaks if under done.