Galaxia
"Galaxia" in fact is the Spanish word for Galaxy, thus the obvious pun. It is also derived from an Ancient Greek word, "Gala" meaning "milk" or possibly "made by milk." Naoko obvious had a thing for using words relating to ancient Greece, so she probably meant to use the latter one.
I also found out that it is the day celebrated by the Hellenes, named for votive offerings made to Rhea/Cybele of barely cooked in milk.
Galactica Superstring and Galactica Inflation
The super-string theory of elementary particles is based on the idea that the fundamental entities are not point-like particles, but finite lines (strings) or closed loops formed by strings. The original idea was that an elementary particle was the result of a standing wave in a string. -- Taken from Super String Theory.
Superstring is basically dealing with other dimensions of space. How the galaxy is held together. Symbolic in that -- this is exactly what Galaxia wants to do, "unify" the galaxy under her power.
Inflation is a simpler idea where it deals with Cosmetology and the creation of the Universe. The Universe is constantly "inflating" or growing larger in size. Also symbolic, Galaxia wishes to recreate the galaxy in her image, without the "Trash" which currently resides in it. -- Taken from Inflation for Beginners.
Galaxia's Sailor Crystal - Saffer Crystal
According to manga translations, Galaxia's Sailor Crystal is known as the Sapphire Crystal. While this is correct, the actual katakana reads it as the "Saffer" Crystal, Saffer being an older, ancient word for Sapphire.
The Kanji on the other hand says "Seikinseki Kurisutaru" or Lapis Lazuli Crystal. While, this idea might seem odd, seeing how the two stones are different, it should be noted that Lapis Lazuli was often referred as to being, in fact, a Sapphire.
Lapis Lazuli is a stone normally of blue color, usually associate with royalty. Sometimes the stone is seen with golden specks of pyrite. It is the traditional birthstone for December and the Planetary birthstone for Capricorns. It is said that Lapis helps one understand the mind. It helps to expand your viewpoint. It is good for connecting the heart and the mind when worn over the heart.
Lapis is Latin, meaning stone, and also from the Arabic, azul, which means blue. When it was first introduced to Europe, it was called "Ultramarinum," which means "beyond the sea." In the middle ages the stone was thought to keep limbs healthy and free the soul from error, envy, and fear. Lapis is primarily composed of the mineral Lazurite.
Alexandrite
The Materials Collection artbook states that Galaxia's image stone is Alexandrite... but does that hold any specific meaning?
Well, it is a rare stone, which can change colors depending on what lighting you look at it under. ( Usually from green to a reddish-purple )
According to myth - Alexandrite can assist one in centering the self, reinforcing self-esteem, and augmenting ones ability to experience joy. The stone was discovered in 1830 in Russia, it was named after Czar Alexander II.
Now, what does this idea have to do with Galaxia? Don't those jewels above look similar to the ones seen in Galaxia's bracelets?
The jewels in the bracelet could be a play on Alexandrite, after all, one jewel is green, while the other is purple. Since the stone is said to reinforce self-esteem, the same could be said for Galaxia's bracelets - it wasn't until after she received them that she started believing in herself more and went on the rampage through the galaxy.
Animamate
Animamate is a pun on the fact that the Animamates are all animals as well. Tin Nyanko (cat), Lead Crow (crow), Heave Metal Papillon (butterfly), Iron Mouse (mouse), and Aluminum Seiren (siren). So in a sense it's like Animal-Mate.