The blastula is an interesting point. I take it that the blastula and the cytoblast both have a common root origin, the blastula being the outer cell membrane holding the fluid within which the zygote will grow, whereas the cytoblast is the actual life organism growing within.
Again, personhood implies individuality, and while the fetus is an individual, they are not yet autonomous as a person should be, so, I steer clear of using that word just yet in describing any fetus. For example, a baby can be counted in a census of population, but a fetus cannot, making the baby a "person."
Exactly. As soon as someone admits that the fetus, zygote, etc., are all just necessary developmental stages in a person's life (oops, I just said person

), no different from a senior citizen, teen, or infant, we immediately recognize the fetus as having individualized human rights beyond just the mere wishes of the recalcitrant mother.