12v+ just means less injection points.
The standard is 5M rolls. You mean 60 per meter, correct?
With the above info, you can calculate the supply size.
One controller can handle thousands of LEDs, but you need to consider the performance you want.
Sorry, correct - 60 LED per Meter, so arround 900 LEDs in summary
With injection points you mean a seperate cable from the power supply to the strip in length?
Is there a formula regarding, how many “injection points” i would need with 6v or 12v? Or maybe a circuit diagramm?