1 - About armor suit - you only need to advance in the game to get the armor, you can't do anything more, only advance and at the point 142 you will have it.I see In the walkthrough that you wrote I read it until the last but it wasn't explained how you got the battle suit armor by the way How can you buy the demon drug from the merchant? First time I met him he ran away also can you change class? I mean when you leveled up to 10 is there any way or person to talk too change it?
2 - About the demon drug - read the point 132 of the guide.