Herbie style I presume. Excellent choice. We're using a dual-herbie design on our 300gal Display. I would use 1 1/2" pipe for both the syphon & emergency drains. That should give you plenty of flow.
I'm a huge fan of biological filtration. I would still include the skimmer for oxygen, unless you plan on another method of aeration. We have an undersized skimmer for our display, but we also have ~400lbs of rock, a DIY waterfall algae scrubber & we're using a surge device to promote gas exchange. We used dry rock & it took awhile to cure, so if you are planning on using dry rock, I would get started as soon as you can using the stock tank.
As far as corals go, those lights will grow anything. I would decide on what fish you want then back into the corals question. Few are self-healing & resiliant, like the kenya tree, but they are also more like a weed & grow everywhere. You can tear them off the rock with your hands & they will still grow back after a week or so. Add one 1" frag & you will be finding them everywhere for the next few years.
I'm a huge fan of biological filtration. I would still include the skimmer for oxygen, unless you plan on another method of aeration. We have an undersized skimmer for our display, but we also have ~400lbs of rock, a DIY waterfall algae scrubber & we're using a surge device to promote gas exchange. We used dry rock & it took awhile to cure, so if you are planning on using dry rock, I would get started as soon as you can using the stock tank.
As far as corals go, those lights will grow anything. I would decide on what fish you want then back into the corals question. Few are self-healing & resiliant, like the kenya tree, but they are also more like a weed & grow everywhere. You can tear them off the rock with your hands & they will still grow back after a week or so. Add one 1" frag & you will be finding them everywhere for the next few years.