UV's

I have a Current 15w uv that draws from the sump and returns the sterilized? water back to the sump. When I bought it the LFS matched a small 300gph pump to it.
Does it work? I have no idea. I mean the light from the uv tube is on and the water is flowing past the light but it is one of those things that doesn't show you it is working except for the fact that nobody in my tank is sick, so... good enough for me.
Everything I have read suggests that they are a useful device to have. Plus they are fairly low maintenance. Set it, forget it and then change the bulb every 6 months or so since the bulb becomes ineffective over time.
As for a skimmer, I have a Euroreef CS5-2 in the sump skimmer. It pulls all kinds of dark brown sludge out of clear water and I don't have a large bio-load either. This thing is super easy to clean and was a snap to figure out how to adjust. At least this device shows you it's working and IMO was money well spent.

I run a 114 watt unit on my return which is pushing about 1200 gph. I added 9 fish with no QT and have not seen any ich and the water is very clear. This is on my new BB set up so I can't comment on wether it helped or not as I have nothing to comapre to. As far as wether you NEED it thats your call. I might look into a larger skimmer before I went the UV route if I were you.

For a FO, UV's can be used, but really, they aren't better than quarantine. Too high a flow will reduce the efficiency greatly--the water must be exposed to the light for a specific time frame in order to work. I've never run a UV, and see no reason to add one. IMO, you'd be better off setting it up on a quarantine tank and using it as needed. For reefs, I think they are terrible--they kill off all the free-swimming larvae and plankton that help feed your animals.

For the skimmer--in a newer tank with a light load, you probably won't see much. Keep playing with it though, and you'll probably start to see more.