Items #1, 2, 3 = Free Inventory Clutter, courtesy of Naddic. I normally throw or sell them. Some quests require them. (It's usually just buff potions for reward)
Items #4, 5 = I would love to know their purpose as well...
Help w/ EXP Data!
Help w/ Server Differences!
Warning to new players:
CLOSERS is a game that adjusts several important details in almost every single patch.
So something that may have been true a month ago may not be true now. Check the date before you reply!