Hey there sbkush. Hope you're well. I see that you are ready to jump on in and get started. Awesome stuff. But before you go to buying hundreds of dollars worth of gear expecting results that you see on Youtube, I highly suggest studying and reading up on as much as you poasibly can. I have some really informative links down in my signature.
As far as different folks getting different yields, that is normal. There is no one way to grow Canna. Everyone has their own ways of doing things and that involves varying results of course.
Your grow and yields are going to depend on SO many aspects that it's pretty difficult to narrow it down to one setup that is the best. That takes well spent time and research and knowing your personal limits/space available, etc.
I wouldn't recommend trying to grow that many planta on your very first real try. I know you say your step father will help, but growing Canna is not cakewalk. And Autos are attuned in their own way too.
I would start with a really simple setup and get that tuned in and all before trying to grow 7+ plants in Hydro. IMHO Hydro isn't the best to learn on from what I see.
I would go with just a couple plants to start. Simple mix, simple lights, simple nutes amd if you start that way, your chances of success are in your favor.
These cats pulling insane yields are well versed in growing. If not, then they just got lucky, and I wouldn't bank on luck.
You need solid material to read that will give you a grasp on the basics.
This will make it a lot easier on you as well as the members here helping you out. All of that is right here at AFN. Everything is sectioned out accordingly and pretty easy to find. I hope this helps and take care. We're glad to have you here at the AFN and want to help as much as we can. Teaching is a two way process though. Peace and hit this with me. :smokebuds: