What is "scharfes"? It looks more like lowercase beta in greek language. We use it in geometry for denoting angles if alpha is already used.
"scharfes s" is a name for that letter; it simply means "sharp s" and refers to its pronunciation or sound.
Yeah, it's not the same. When you meet someone, you say "Hello!", but I don't think you would say "Grettings!", that would be funny. You can often see it in writing, for example at the end of a postcard: Viele Grüße aus Deutschland! Dein Tim - Many greetings from Germany! Yours, Tim
If you hover over the mouse on the word, it shows the gender is masculine. But why it was Die Grube?
Yes, the gender is masculine: der Gruß (singular). die Grüße is the plural form. Does that answer your question, Parexel?