As with all hobbyists, the choices are totally up to you. Now I'm not really a fan of high tech as I think that although it may be great for plants, it can be very hard on the fish. I've participated in a planted tank forum for quite some time and lost track of the times a CO2 system malfunctioned and killed all the fish (and suffocation has to be a terrible way to die). Then there's the 'famous' EI (
Estimative Index) method of dosing large amounts of ferts to better ensure plants have all they need. Just can't see how that's good for fish as anything and everything in the water invades the livestock through osmosis.
And then you mention FAST flow (filter?). Good filtration is about how well we filter water, not how much or how fast we push water through media. And bio-filtration happens best with a slow, steady flow of water. Oh, I know manufacturers tell us we need 8x to 10x water flow relative to tank size, but that's largely self serving marketing hype that hobbyists tend to parrot all over the internet.
Okay, perhaps that's enough of a 'rant'...maybe.
When it comes to numbers, very often more of a species can be better than few numbers, but may be limited based on tank size and setup. An all male population may promote aggression but frankly I colony breed my fish and have no real population control experience.
Best wishes in your hobby adventure.