questions and assumptions??

[BCReefer]

I have just almost finished reading Concen. Marine. So I have a few questions and assumption:

1. When I use a sump, I use LR to improve my filtration. This would replace the need of a mechanical filter.
2. Use a Skimmer
3. When using a sump I need a way to move the water from the tank to the sump, thus I need to have a hole put into the tank and use appropriate connect/disconnect plumbing hardware. I would assume you would need 2 holes 1 to the sump and 1 to return to the tank?
4. When using HO or VHO ensure that you have proper ventilation so that you do not overheat you tank.
5. Ok so what is the difference between a sump and a refeguim ? (Not sure of the spelling there)
6. There must be some power heads to create water circulation.
7. When adding new water you add it into the sump???
8. You add all your chemical in the sump?
9. Have a good base of sand or substrate.

These are, as I indicated earlier assumptions and questions that I have. I have been reading as much as I can and I want to ensure that something is staying in.

Thanks for the help and comments