does the oil have to be a certain temp for frying or is "really hot" OK?
The oil should be 375 degrees if you have a thermometer. If not really hot I find to reach 375 it takes about 15 minutes
You can test the oil by putting a small trial piece in it. You want it to cook quickly so that it does not absorb excessive amounts of oil, and not be overheated -- oil that is smoking is damaged and not healthy.
I agree with sdebrango on the temp. And be careful about which oil you choose, per susan g's point. A frying oil would be grapeseed, canola or peanut oil for their higher smoke points.
I always use this trick I learned from the Canal House Volume No. 1 by Christopher Hirscheimer and Melissa Hamilton:
Their friend Julia Lee (whom they call the fry queen) uses the chopstick test to see if the oil is hot enough for frying. Dip the wooden chopstick (I use a skewer) into the oil until the tip touches the bottom of the pan, if lots of bubbles form right away around the tip (like champagne) the oil is ready for frying.