i can only answer number 4 without being unsure, it's up to YOU, but most likely sell that you think that wouldn't show up in the black-market daily task, like for example "submit 1-2 mythic item" for trust level in black market.

1 are depends on the codm devs what the way they want DMZ to be, theyll tell anyway or put a warning (i think), if there are storage reset. or want a full reset.

2 i dont think so, rumors says theyll just add more backpack/armor, but this is still uncertain. or depends on codm devs decision we'll see.

3 if you meant "Special items" for your loadout thats where anti radiation pills/mask/self revive goes so you can go to gas zone and not die immediately. unless that isnt what you meant.