Any time, ask as many questions as you like.
Qt is best practice but something that the majority of people do not have or do. The kiss methods applies and it's usually best to grab something like a standard four foot tank with pine stand and a large canister filter and heater and that's it done for about $400. Its not so much the expense but the pita of running two tanks and once you have your display up and running these usually get shut down and are just taking up space in your garage.
I buy my fish small as they seem to adapt better so Im using an 18" cube I has with dosers, ato and auto feeders so it runs itself. Ideally it would be larger but after the initial set up phase it should be just for one fish at a time max.
Ro di, everyone says this but there is a reason. Speak to Pete at psi filters he will do discounts, give you the best equipment, advice and price, if you don't walk away preaching about him like everyone else I'd be amazed.
I do 200l batches and store it in a rain water tank, in the right containers it can be stored for many year. Salt water you can either collect it yourself from a region like rose bay or mix up artificial water with a synthetic salt and do water. Generally you add around thirty grams of salt mix per liter of water, put in a pump to mix it and let it sit overnight, you then test your salinity with something
Ike a refractometer and add some more salt or water go get your levels right.
You basically get what you pay for bright well is by far the best and most consistent with its levels being near perfect each time, Then you have your red sea! d and d and a few others that are really good as well, cheaper in price and suitable for most systems.
Just to throw some confusion into the matter have a look at the new red sea s 400 tanks, full star fire, great quality, just about everything you need for 4k with a chiller in the cabinet.