I'm working on understanding Polish grammar and thought I would share my thought process as it may help others, and to check if my understanding is correct.
Znamy is used because we want to describe the people doing the 'knowing' in the 1st person plural (we).
Odpowiedź is used because the 'answer' in this sentence is in the accusative case because it is the direct object of the action (to know).
No, it's not. Your level in Spanish is lower, but maybe it helps you to know that "wiedzieć" is like "saber" and "znać" is like "conocer".
Anyway, see here: https://forum.duolingo.com/comment/25535826
tl;dr: "wiedzieć" is for "to know, that X", "to know about X"; while "znać" is for "to know X".