Do I need to get Dragon Plate Armor for everyone in my party? I only found two silver metals to have forged.

No, just the fellow in the lead! I thought you were napping! LOL!

Lily, you must be wide awake. An answer in 1 minute and 7 secs!
And right again!
Nancy, you can get more dragon plate armors if you like, but not in an honest way. (Everybody can wear them!)

(Steal dragon ore from Freyedies, and he'll make another set for you; steal the key to his treasury and find another one.)

Right place at right time. But your answers are more complete! I just fill in when the answer gods and godesses are busy elsewhere!