yeah well, I know a human brain doesn't work as fast as light speed, but data in my VR networks can.
All the computers in my universe make use of quantum speed processing units, now I don't understand quantum theory so I am essentially saying It can do what I want because of quantum! but as they are all basically super-fast quantum computers and they communicate via FTL networking which exploits some glitches that happen in physics at the quantum level. I can do magic. so there.
You are perfectly entitled to use Handwavium but I'll be totally honest (as someone who is your ideal reader and the sort of person to buy this book) the whole FTL thing doesn't make any sense.
Light speed and FTL are different, you can move data about as 1s and 0s at the speed of light now - or close enough. The point is that human beings have to interact with the VR, if the VR is FTL or not has no importance whatsoever for the human interaction.
Quantum computing has nothing to do with speeds, it's essentially using indeterminacy so that a single bit can be a 1 or a 0 or both, which means a bit can be used in more than one calculation at any single time. This would be useful in your world for massive amounts of data processing but again it wouldn't really be required as classical computers could scale to that function (arguably their generality would be better suited to those sorts of tasks anyway).
I think one of the problems writers face when writing about tech is that techies love to read stuff and pick it apart, probably one of the reasons a lot of authors write in generalities, ie: we are told Ender hacks the networks, we are not shown how it is done. This is essentially the science problem with a tech twist.
With regards to interface management - Ready Player One has one of the best descriptions of this I have read, it essentially becomes so baked into the story and physical actions once the framework is in place you don't need the specificity, very easy to imagine Wade doing what is described and also the how of it.
You can always wave the magic wand but I would just caution against using Quantum Computing just because it sounds cool, it draws attentions to the science and also might age badly.
Anyway these are just my opinions. I work in the tech field so if you ever wanted any specific advice I would be happy to respond to a PM!
I don't want this to sound critical I promise I am only trying to help.