Amoebae move by growing an extension of their bodies in the direction of movement and then flowing into it. This extension is called a pseudopod because when it's fully extended it resembles a limb, despite being only an extension of the amoeba's plasma membrane.
Yes you can. The atomic mass measured from the proteins and neutrons in an atom, since you know he number of protons, you can subtract and be left with the number of neutrons.