I think it had better be explained where Node-Red fits in to all this.
As you said there is a plethora of WiFi switches out there.
Likewise there is a plethora of ways to do what you want.
I think some of your confusion is where/how Node-Red fits in to all of this.
Node-Red is a program (to call it) that allows a lot of things to be done. Including WiFi control of lights.
HOW this is done is a whole other set of things.
You could control the WiFi switches from Node-Red. This would involve learning the codes sent by the switches and replicating them. There could be a library (or node as the term is here) that supports your WiFi system.
You could build simple hardware outputs from an Arduino to then "electromagically" press the buttons on the existing remote control.
This way would involve hacking the remote control allowing electronic button pressing done by the arduino.
Basically putting a FET in parallel with the button you press.
Then, make a "dashboard" which looks like the remote control and when a button is pressed it sends a signal to the arduino and it "electromagically" presses the real button.
I'm not going to say which is easier. You are going to have to work that bit out yourself.
Designing dashboards isn't too complicated. I have done it, so that says a lot.
So all this about:
Well, that's at a different level. Node-Red is software. That is hardware.
You have to work out how to get the software to control the hardware.
Again: There are many options. My love for switching "mains voltage" (don't know your local term for that) is relays.
Sure they are "old school" but they work. They provide a simple "on/off" switch and easy to associate with logic levels at the software part.
Dimming is a whole other field. I don't know enough on that to suggest solutions.
Other than LED STRIPS are great and offer a whole lot of options which are easy to implement.
It just depends on how much light you want....
Again: I can't answer those questions. Only you can.