Nothing in the code I know of requires arc fault upgrade on a panel change. But if you need to arc fault a MWBC, use a DP breaker. I use them on new construction.

 

IME, depends on the AHJ.

When I did my own 200A service upgrade, I sub-fed the original 100A. The inspector didn't even want to see the old panel. He said it wasn't in the scope of work.

 

210.12(D) says you only need to install AFCI protection when extending the circuit over 6 feet.

 

As mentioned above, the AHJ will have the answer you seek. My limited experience is that a flip from fuses to circuit breakers does require a breaker upgrade. Increasing the service size or increasing the load will require the upgrade. Ask first to avoid a frustrating and costly surprise.

 

Things might work different in your area. Where I am and I believe most of the US, we go by the adopted code. The AHJ has some discretion when it comes to something that is up for interpretation, but they don’t have the ability to make their own requirements willy-nilly. The NEC is very clear on this.

 

No, but here we are required to replace 2 wire ranges, ovens, and dryers to 3 wire and install GFCIs