My honest opinion is start smaller to start. Even a 5-10 light setup will be hours of work daily. First time indoors if shit hits the fan you need to be properly prepared. Last thing you want is to get mites on your first run on a 20 light setup…
My suggestion is just lightproof a solid portion of the room and do like 8 lights to start or something. Do 3-4 lights in veg and 8 in flower. You can ALWAYS add more clones very easily.
Look into solid lights - CMH and Quantum boards are super popular for getting up and running quickly. Alibaba has some pretty solid choices as well that I’ve seen recently. I forget exactly but if you search mammoth 10 bar you can find the same exact light on alibaba for like 400-500 a piece.
Dehumidifier + AC unit + fans + controller with sensors.
IPM I can not stress this enough. Before you even buy your equipment have a solid IPM in place. Most commercial programs you will need to hit the plants a few times a week with multiple things throughout majority of the cycle.
Nutrients, genetics and feeding. Loads of info on the web. Basically comes down to your style
C02 - Figure this out when you are designing your room. Properly used c02 as far as i’m aware will up your yields by like 20%-30%. I’m pretty sure it speeds up cycles significantly.
These are just the very very very basics. Talk to someone like @Demontrich or anyone else. They key here is to PUT THE MONEY UP FRONT IN THE BEGINNING. Buy quality to start or you will regret it later. I am by no means a professional and would 100% recommend paying for a consultation with one of these guys.