Kudos for reading first, and welcome to AquariumAdvice.com
lets see if I can tackle all of these...
first, A sump/fuge is a good way to go.. I'll be tackling this challenge myself as soon as I finish my new tank stand. You can partition the tank if you'd like, but, IMO
, there's no need. the difference between a sump and a refugium, is a refugium has additional substrate/LR
/MacroAlgaes etc, whereas a sump does not. You could use the entire 30 gal
as a refugium, and still put in your skimmer/heater etc in there, it wont affect the refugium.
You won't have to worry about things running dry as long as you don't let it all evaporate ;o) (laugh as you will, my tank evaps about 1 gallon every 2-3 days this time of year) in your main tank you will have a HOB
overflow that you either buy or make, as the water level rises in your main tank it will spill into the overflow and down into your sump/fuge which will them be pumped back up to your display tank, raising the level in your display tank, and again, overflowing into the sump/fuge.