Fourth...ed? I do this all the time for my clients. It's a great way to expand wireless in the house.
1- I don't believe what we're talking about is a repeater (someone correct me if I'm wrong, I probably am...). Commercial WiFi repeaters, IMO, are the devil, and when you make your own with WDS you're hobbling your wireless network. You're merely adding an additional hotspot to your network.
2- If you're reading this and you're like "darn, I'd like to do this but I don't have ethernet going through my house," I would suggest something like this product
if you have coax in the rooms you need. I've used MoCA adapters like these to great effect, and the speeds are great, especially compared to powerline, which is a last resort. I prefer the Netgear MoCA adapters before, but they seem to have disappeared from Amazon, which stinks.