Alright, so, little confused here.

With Auto-Fire, you increase the Difficulty by 1. You land an additional full hit for each Advantage.

With Two-Weapon combat, you increase the Difficulty by 1. You land a hit with your second weapon by spending 2 Advantage.

Now, with Walking Fire, you increase the Difficulty by 1, and then "generate hits". It doesn't specify how you generate the hits, so I'm assuming you use the applicable method from the appropriate attack-type.

Does the extra Difficulty from Walking Fire stack on top of what you already raise it? The text for Walking Fire says it is an -alternative- to the other methods, so it really isn't clear. However, if it uses all the exact same rules as Auto-Fire and Two-Weapon combat mention separately..why give it its own section at all?

So, would Auto-Fire Walking Fire be +2 Difficulty with hits generated per Advantage, and Two-Weapon Auto-Fire be +2 Difficulty with hits generated per 2 Advantage? Or would it still just be +1 Difficulty on either shot?

Auto-Fire adds +1 Difficulty before we get to chosing any specific type of attack. It's just one of the barbs associated with the weapon quality.

SO in the Auto-Fire + Walking Fire scenario I'd add it up as +2 difficulty and +1 Drawback to the pool. Then for Auto Fire and Two Weapon Combat I'd break out the yikes machine and add +1 difficulty for each weapon featuring autofire and then add +1 for Two Weapon Combat for a total of +3 difficulty (+2 if only one weapon was autofire capable). In either case the active character could spend Advantage and Triumph in any way they wished given their options listed in Autofire, Walking Fire, Two-Weapon Combat.

Imagine Autofire+Walking Fire + Two Weapon Combat featuring two light weapons with autofire. +4 Difficulty and +1 Misfortune to whatever the starting pool looked like.

On the upside, Autofire makes it really easy to spend Despair as a GM. "You hit <insert something the player shouldn't or wouldn't want to hit>"