I'll have to agree with yC as well, there are too many issues with what you plan on doing. You may have good intentions, but that's not good enough.
Also let's not kid ourselves here, and sorry if you find this harsh, but your developper is fully aware you're incompetent (and that is how he sees it no matter how nice he may seem). You're not in control of anything here. Scripting is the easy part and it's pretty much a requirement to know how to script as a server admin.
How about the rest? The source is one thing, but more importantly, do you know how to manage your VPS/dedicated server? What if your server crashes?
Or I don't know, what about your SQL capabilities:
- What if your website's SQL account privileges aren't set properly and someone deletes your whole DB through SQL injection? How are you going to handle that?
- What if an ex-admin uses his database and decides to log into known accounts to mess up players? Will you be able to do anything to resolve that?
- A more common case, what if someone asks you to return his item because he sold it to an NPC?
Or on the script side:
- What if someone reports a buggy NPC?
- What if an NPC is exploitable and requires immediate fixing?
- What if... a planned event you wanted to run on your own has an issue? "Sorry guys, I can't... find the problem, we'll try that again in a few hours when I talk to my guy!"
I don't know the extent of your knowledge, but if you're asking if it's feasible to pay someone to code your whole server, I assume you don't know too much about managing a server to begin with. You don't need to know everything of course, but you need to be willing to learn how to script and how to modify your sources.