Mary no ha matado a ningún personaje importante hasta ahora. Principalmente porque en la novela ligera no es ninguna amenaza.
El Batallón 203 ha perdido 10 magos en la Batalla de la Reina de Anjou (que veremos en la próxima 2da temporada), pero ninguno de ellos tenía nombre y es más probable...
It was probably made up by someone who doesn't get attention at home and wanted to appear interesting.
Yutaka Huemura also spoke about it with WebNewType and, as the anime's director, wanted "each character's design to reflect their character and personality."
That's a hoax. The author didn't ask for anything regarding the character designs; that's just Yuuji Hosogoshi's signature drawing style, and you can see this from his previous works. According to the WebNewType interview from february 2017, Carlo Zen didn't want to be too involved in the...
JP to SPA translator here.
Yes, you're correct. "White Silver" is her official alias, but she's rarely referred to as "Silver Wings" in the manga, and also as "the one with the silver wings". Mangaka sometimes alternates these names.