I use a 200 mg/hr RedSea unit on my 250 tank going through my beckett skimmer and love it!
I have an ORP controller but I would go w/o it if it broke down. I don't think you need one if you inject the appropriate amount into your tank.
I don't use carbon (many do and it is not for excess ozone, but for the by-products of ozone in the system; chlorimine and bromine).
My tank has never looked better, and takes less maintenanced with ozone. In the long run saves money because I no longer buy carbon.
I say go for it, you will love it.
BTW I do recommend venting the skimer outside, it tends to really stink with O3.