Sounds like you're trying to make an auto follow spot.
DMX is easy there is an arduino shield and library for DMX control which I've used with great success.
However I suggest you likely need a good level of accuracy to get smooth operation, in the range of 1/2 a stride.
Getting the location from wifi would be very hard. But I wonder if you could measure the time for the actors wifi signal to get to points (at least 3) in the room and then use calculus from there. of course reflections will cause all types of issues, and really you don't need wifi any radio transceiver will work, but you'll need very accurate timing pushing you to fast and synchronised clock speeds. Wifi might have the benefit that you can use server time but latencies will cause huge issues.