BecomeMe

I think the idea is probably that it would need a lot of simulated data/interactions. I could see a case for both believably of the simulation (particularly with our pattern-seeking brains) and just the normal and long-term operation of the brain.

On the second part, think about how things like inner ear problems and de-personalization exist. Or agony that comes with a plugged ear or nose. Imagine if you lost the sense of weight, pressure, or temperature... or perhaps even just lost accuracy (or gained delay) of it: do you think you would move the same? Do you think it would have any effect on your brain over time? This goes particularly for someone who grew up with a body, I don't think it would be unlikely for most people to have some kind of dissonance from noticing inconsistencies. (now if the thought it it's always been in a vat, that doesn't make as much sense, though that could lead to the argument that it would create developmental differences or at least lack of attunement to physical life EDIT: also garbage-in-garbage-out, particularly even just the quality of socialization for your entire life)

Of course I think something like brainVR could work if it was something you were aware of, but even then it would probably be better to just patch in (or not interfere with) sensory data from your body/local environment.