Update your post to include full system hardware specs and OS.
Include PSU: make, model, wattage, age, condition.
There are likely a number of varying answers to your questions.....
However, what you must really do is to take a close read of the motherboard's documentation, the case documentation, and any other documentation associated with RGB fans, hubs, etc..
Unfortunately you cannot go by the commericial ads and other marketing materials that, more than likely, will leave the impression that all will happily work.
Details matter and RGB is very much a source of confusion just on its' own merits.
Read the documentation. In many cases, the documents will refer you back to the applicable manufacturer's websites for updated information.
Do that as well. Pay close attention to all warnings, notices, fine print, caveats, and so forth.
Then sketch out your planned installation of fans, hubs, connectors etc. down to the pin level.
Connectors are likely to be named differently as may the connections coming from the case or other components. There are standards to some extent but you cannot rely on all parties/components being immediately "plug and play".
And if there is a need for RGB related adapters be extra wary. "Compatible with xxxx" is a warning in itself. That may simply mean that Plug A will physically connect to Connection B. No guarantee that the end result will work.
Read the software documentation and the remote control documentation. Understand what can actually be controlled/configured and from where.
That all said, I will also suggest that you think about the overall build. For example: Are six fans really needed? And, if so, the actually physical installation also matters - otherwise all the fans could be fighting each other and the desired end cooling reduced.
Just my thoughts on the "bigger picture".
Not anti-RGB per se. But failing to make the proper connections and configurations may, at best, simply not work.
At worst there are sparks, pops, and smoke.....