Can someone explain an XCAL, what it is, where do you get one, and how much does it cost.

www.sctflash.net

Click Ford Flash Devices

Many more threads here: http://www.lincolnvscadillac.com/search.php?

can u really adjust everything yourself?

Not everything, no. Prevents people from blowing up their motors that way.

You can make MINOR changes to a custom tune before you load it, wheel size, timing, and idle, air/fuel adjustment, transition shift points, and line pressure, turn on/off speed limiter or set the speed.

You can not write a tune.