3. Inventory - It felt a little slow with the Drag & Drop system, which reminds me when Minecraft had a similar feel to it, then they implemented the option to "SHIFT + Click" for an instant deposit/withdrawal of items to the nearest available open slot from top to bottom. As well as Left -click to pick up stack of items, Right-click to put down one from the stack or Left-click to put down the whole stack again. This system seems Simple and VERY convenient, also looting dead bodies and mobs would be faster in my opinion.
Probably intentional so you cant quickly loot things, especially players bodies in PvP. They want you to be vulnerable while doing that, they want you to DIE.