Looks like a great location, love the curved walk.
Has anyone built there own adjusting weir skimmer?
Yes.
Instructions
Am I on the right track thinking that if I have a pump inside a wall skimmer with a uv light somewhere in there that would a good setup?
I like and use that set up. Some people say to put the pump at the pond bottom to rotate water but when a pipe breaks, raccoons move a filter, the pump drains the pond and kills the fish. Happens. In the skimmer no problem and water can be directed to the bottom to get the exact same rotation.
UV is a good way to ensure no green water. Generally you only have to run them for a few weeks and other algae will stop the green water. With the UV if you get green water it means there is something wrong with the UV...too small...too much flow....installed wrong....old bulb...etc...
24/7 trickle water change is another option for clear water. But for your climate and yard size I assume the overflow water would not be useful in the garden. I would consider having an overflow pipe. Heavy rain can overflow a pond and generally in the worst possible way. Better to have control.
I like a catch basin that the base of the waterfalls. Still water for better viewing and no foam on surface. Will also direct water to the bottom helping to keep the bottom clean, better gas exchange, and free.
Too keep a water garden (rather than Koi pond) clean
I like vacuuming. Especially in a small yard.
Water changes, which can be part of vacuuming, also help.
Be careful of filter recommendations, actually all recommendations. Everyone has an opinion and their filter is always the best. But often their filter actually does nothing. There was a very nice lady in one forum with an absolutely stunning pond, most impressive I'd ever seen at least in photos. She chatted a lot but never really gave details on how she ran the pond. Then once she did and explained her filter. It was a kind that people had given up on years for not working very well, so that was strange. Then she said she also did water changes and it turned out to be a little over 33% per week. That's massive and completely explained the perfectly clear water. She also cleaned the underwater rocks regularly. She continued to believe it was her filter and unfortunately was a bit upset when others suggested otherwise. Sometimes you have to look beyond what people say and see what's really there.
Looks like a fun project.
of where im at with designing this. One picture is a view from the deck area at back of garden and the other from the house side. There is a large concrete mass right in the pool area shaded grey or black in the photos and labelled boulder. I cant move this so it has to be taken as the shallow end maybe 12 inches deep as a guess right now. Im going to skip a self build on the skimmer and fork out for this ... 
