You can use a small brass brush to clean the fuses and holders if you have one. Be careful not to break the rather fragile material of the fuses with what ever you use.

The air mass meter (AMM) meters the amount of air entering the intake. That is why vacuum leaks need to be addressed as they allow unmeasured air to enter the intake and the fuel injection system needs to know how much air is entering to add the right amount of fuel.

The vacuum at the hose attached to the FPR should be be the same as any other vacuum measured in the system, the exact amount I don't remember. It flucuates with throttle opening and engine speed.

Randy