I have an SWC skimmer (Salt Water Connections.) The one I have would probably be a great size for your system. It is the SWC 160 Cone. You can search google for it. I think it runs about $250, which is very cheap considering how well it skims/is built.
This is an in sump skimmer, not one you can hang on. Not sure if you are putting in a sump or not (i would recommend, as it is great for the livestock and keeps all the equipment out of site.)
A lot depends on how big your sump is, how tall the stand it, etc. The skimmers usually sit in around 9" of water, so you have to set them on a little stand in your sump. This makes them a bit high, so often run into trouble having enough room. Good to pick a skimmer and think about this ahead of time. The high issues are why a lot of reefers end up building custom stands.
As for RO/DI filters, there are many sponsors on this site that sell good products. (fire and ice comes to mind.) I got mine from thefilterguys.biz, and I also think they are awesome. If you are ever in seattle, I have one sitting in my basement... pm me if you may be interested in that and we can discuss.