Like Ted said, the volume of the sump won't matter to the DT. especially just 1 gallon. You should consider upping the size of the refugium too, that way you can host a nice DSB and some good cheato. Even just a 5 gal bucket would suffice, but be careful with water flow in there, low flow is good in a refugium. Maybe consider one of the waterfall filtration things. Those work awesome, I was blown away with how much algae that thing caught.
You want at least 1lb per gallon of live rock, but it's best to go higher if you can fit it.
For lights, I use the 120 watt LED's you'll find on ebay from china. I buy from super qui-qui, and get great deals on dimmable lights (this is a necessity, these lights are so bright, you NEED to be able to adjust the blue/white ratio, or tone them down all together.)
Are you planning on coral? because if not you don't really need LED's and could get by with some lower end lights with just fish... and if you are planning coral be careful with the Angelfish, i've had issues with them eating zoa's and stuff. They are hit or miss with this, but it sucks when they nibble 5$ of coral here and there.