Depending on what you plan to do with the coke hats/shields/earrings, you could either make them entirely increase on stats (XML edit the incSTR, incDEX, etc nodes), or you could always just give out items with stats for reward or something but the actual coke items remain untouched (using the server to give that item with unique stats).
Drop data is all handled in MySQL within the monsterdrops table I think back in Odin. The drop rate of the item, depending on what you want it to be, must be set properly. If I remember correctly it should be ranged from 0~99999. 0 being 0% chance and 99999 being your 99.99% drop chance, pretty much every time the item will drop. One thing to note is you have to include a mobID to drop the item. If you want multiple mobs to drop the item, or every mob, then you'll have to add them to the list in the DB too.
Modifying the MobHP should just be as simple as what you're editing. Modifying maxHP to a valid int32 value (0~2147483647) within the "maxHP" node under the info property will update the mob's HP when it is parsed. You'd need to save that XML and restart your server so it can reload that XML. If you make it too high, it won't work or will mess up the HP because it's trying to parse a signed int.
Might I suggest reading some WZ tutorials or just playing around with them a bit? WZ Editing is fairly easy to get started with after seeing how it's done, which you can probably already tell since you were able to find and edit the mob's "maxHP" value already.
EDIT:
Maplecretes I'm not sure what specific stats you're trying to edit, but remember after editing the item's XML you'll need to again, restart the server and re-make the item for it to update. Remember that "req" is required stats, and you can't add requirement stats in just XML, that will actually need to be updated within your WZ files itself. As for your "inc" stats you've included in the screenshot, "PDD" refers to Weapon Defense (Physical), and "MDD" refers to Magic Defense. So you're increasing WDEF/MDEF both by 12 on the shield.