bleachandvomit

I have a few questions pertaining to overflow mechanics. Ive decided on a 45g cube with an external overflow, however, I'm uncertain of what's best.

1. Do Durso overflows rely on siphon? I'd like to avoid any kind of suction and go with something that "drains" based off of the return pump's output.

2. I see lots of 6 drain-line complex plumbing mumbo jumbo setups around. Is this necessary? I was planning on just having a 500gph dual 1" overflow setup and I want to know if this will suffice.

3. Say the power goes out. With a durso setup in an external overflow, the only water draining to the sump will be what's in the external compartment? If the return pump is off, I don't see how things go awry if there's room for a few gallons in your sump.

I can't seem to formulate any more questions but if anyone could give advice or tips it would be appreciated!