this is in regards to action potentials.

Question

they do not affect the membrane potential of neurons.

they increase in magnitude as they travel along an axon.

they can be measured by using electodes.

there is a loss in signal as they travel along an axon.

just doing basic web searhc i lean towards the "there is a loss in signal as they travel along an axon."

No, the signal is constantly replenished by the Voltage gated challels.
You can measure them with very small electrodes.