Are Wizards supposed to be able to take Earthquake?

I dunno who i should ask about this, but are Wizards supposed to be able to take Earthquake?

What kind of action is it to use a spell scroll?

Does Cone of Cold kill you if you drop to 0 hit points?

Can I command my Find Steed mount attack seperately while not mounted?

Can a PC with mage armor benefit from carrying a shield?

Do you need Find Familar or Steed prepared in order to use the features?