Question for the beananimal overflow experts

[Werbo]

I thought the full siphon would be broken. Thanks for confirming.

I will have a large 42LX12DX5W external overflow.

1. Do I fullly submerge the full siphion?
2. Does the secondary drain set the level of the overflow? What should the level of the overflow be in relation to the main tank?
3. Is the emergency drain approx 1 inch higher than the secondary drain?
4. The top of these stand pipes have any special plumbing. Anything similar to a durso? Or strainers to keep fish out?

Sorry for all the questions but this will be my first proper overflow. I you have a similar large overflow could you post pictures of your beananimal. Thanks in advance.
Tyler