Can you do that yourself or would you need an electrician to sign off? What about your landlord?
I agree in principle that this is much nicer in theory. Just like wired is more reliable than wireless. However, retrofitting all that is also much more difficult.
Depends on where you live. In most jurisdictions in the US it's generally OK for a homeowner to perform "like for like" replacement work on their own residence without a license or inspection. This means you can replace an existing light switch, or an outlet, or a breaker. You generally cannot run new wire or new outlets without a permit.
If you own a property but don't live there (eg, you're a landlord), it's essentially never legal. The best answer is to contact the local AHJ.
I agree in principle that this is much nicer in theory. Just like wired is more reliable than wireless. However, retrofitting all that is also much more difficult.