On your residence, nobody can open chests but you. You can give people access to opening your chests via flags but it's recommended to only do that to your own accounts. Anyway, it's cool you've found EMC so early in your Minecraft life! It took me some years to discover it! Have fun!
Thank you guys for the responds, sorry for the many questions but in the marktplace I saw things like stacks, DC and Sc? what does that mean? I assume a stack is 64 items but what about the other two? Thanks!
SC is single chest (27 stacks) and DC is double chest (54 stacks). As far a stacks go, this is the highest quantity an item will "stack" to. Typically building materials will stack to 64, some items to 16 (ender pearls, buckets etc.) and some items will not stack at all. In the case of a DC of potions, since these will not stack, 54 total potions would be considered a DC since it fills a double chest. Also, welcome to the Empire!
Empire LinkHUB has a ton of helpful links - https://empireminecraft.com/threads/guide-empire-linkhub.55968/
This is a huge help, I have it bookmarked and always share it with others. ^_^ Each server or Smp has its own unique economy. Example: at one point all the shops on smp1 where out of ender chests so 1 shop owner was making a nice little profit selling them. Even though other shops on other SMP's had them stocked. So just really shop hop to get a feel of what sells the best on you're home server ^_^ Lol that's my 2 cents, but I'm not really know for making a profit I prefer giving things away if I can afford it