The WPG rule breaks down on larger tanks. 2-2.5 WPG on a tank that size is A LOT of light.
low light and no CO2 will greatly reduce the plant selection you have to choose from.
They're not quite as expensive as reef tanks from a stocking perspective because you can get your plants here from other hobbyists and they grow much faster than your corals will. From an equipment standpoint it is expensive as a reef set up if you do it right.
The overflow and sump will be fine with or without CO2- the only thing is if you do use CO2 the trickle plate and bioballs will outgas your CO2. (its basically the equivalent of shaking a seltzer bottle- the agitation causes the co2 to come out of solution) so you will either have to reduce the turbulence (remove bioballs and trickle plate) or close the system to keep your CO2 concentrations up. They are also great for hiding equipment like heaters and such that you don't want in the tank.
No controller is necessary to dose CO2. Just work your way up slowly to desired concentrations with small adjustments a little at a time so you don't end up overdosing and suffocating your fish. A member of my local club says the "indicator" he uses is "upside down fish" If they're upside down, its too high, when they right themselves, its just right. I AM NOT RECOMMENDING THIS- its a joke, but its close...
Canisters are great, and you will probably end up with one eventually, either to drive more external equipment or to increase your flow but they are not necessary to get started.
I would go high tech CO2 off the bat. IME, you just won't be happy without it. CO2 is so important, for battling algae, increasing/improving growth, expanding your options for plants you can keep successfully, and lets not forget the pearling... so so pretty.
As for running the bulbs.. I'll leave that to the experts, I am sure they'll be along any moment...