Seems to be very popular in Texas. Both my previous home north of Houston, and my current home north of Dallas are Post Tension Slab. The soils really expand and contract with moisture, as they have very high clay content. This puts lots of stress on the foundations. This is my understanding for such foundations here.

In summer you are advised to "water your foundation". During high heat you don't want the soil around your foundation totally drying out and cracking.

I'm in Charlotte, NC. Lots of clay. Never heard to water my foundation, however.

The town may have your house plans on file, wouldn't hurt to call.

You should run a CAT5 there, too, so you can plug your laptop into the power and look up those recipes you'll need. Think about where you might sit with the laptop, probably near but not directly adjacent to the desk, and put it there. Put more than one electrical outlet, too. Every island I've seen with power could always have benefited from an additional outlet on a different side.

Talk to an electrician.
Pay them the 1 hr service call and get all your questions answered.
In eatery, NEC dictates no more than 4 outlets on a circuit. There are also code requirements for max distance from edge and between outlets. You may need 2 or more circuits for this. There is also obvious requirement for GFCI, but there may also be one for ArcFault if one side of the island is considered to be in another room (living rm, hall, etc).

Oh, yea. Definitely run an empty conduit for future low volt for crap you can't envision today.

You will want it there as well. There reason it is code is so people don't string extension cords across the path to the island. It is well worth the effort to do it right so some kid doesn't pull a hot crock pot off the island onto themselves.