Noobie needing tips

[jason604]

Hi there I'm planning to get my first saltwater aquarium set up and I have a few questions. I'm most likely planning to get a pre-owned set up about 75+ gal with hopefully led lights as I am having coral. I'm from Vancouver so I'm wondering would I need to also get a chiller or will the led light not make it that hot during summer compared to a MH light? Do I need a sump and what is it for? If I get used live rock/coral/ fish if possible do I have to do anything to them first to disinfect them just in case previous owner had bad things living on them? Also if I end up buying live rock that's been out of the water for a long time would they come alive again? Can I add fish and coral right away if live rock is established but totally new salt water?

Sorry for all the noob questions but I want to get everything right the first time so I won't have to make horrible mistakes n lose massive $$ and time. Thanks in advance