Creating an RPG, even a smaller one (10 hours instead of 80+ hours), is quite a daunting task for a lone developer. The amount of content needed for even a small RPG is staggering, even though the programming might not be as complex as for some other game genres.
And note, I am not talking about anything "Online" yet. Let alone "MMO". I am totally in agreement with the other guys in this thread. Follow this list if you want to get anywhere:
1. Banish the thought you will ever, ever create what 80% of people understand when they read "MMO"... that is massive amount of concurrent players interacting in a single instance, massive amount of content, and so on.
If you are not working at a VERY LARGE studio that is working on such a title, that is. And these are massive projects, and given the track record of past MMORPG projects, less and less of these will be made in the future (which is good, the world can only support so many active MMORPGs... as opposed to other RPGs people burn through in weeks, these things are built to engage players for years, which leaves little room for playing multiple MMORPGs at the same time).
If you want to start your own, you better be a billionaire playboy with millions to just burn. And I mean "burn" literally, chances are pretty bad you see a return on investment, not unless your MMORPG is so revolutinairy and good that Everquest, WoW and all the clones pale in comparison.
2. Put your "Online" aspirations to the side for now... they are quite achievable for a lone dev, or better a small team, but you are not ready yet for that. You have more than enough to learn otherwise.
3. Start creating singleplayer games. Better start with simpler ones. Work your way up.
These questions you put up there would answer themselves if you did your homework in advance... does it matter to your Online Game Project you start in 5+ years if you create your simple pong or pacman clones today in Java or C#?
Of course not. Ideally you are able to learn and program in multiple languages, and while doing so, you will find a) the language you like better, and b) the framework best suited to your use case.
Trust me, you are about 5 years to early for creating an Online RPG (lets put the "MMO" monicker to rest right here)... maybe 3 years if you are able to spend A LOT of time on learning, or can team up with other people and thus concentrate on one specialization.
But we are talking years before you could even think about being productive creating something so complex as an online game.... before you would get no traction at all as you would just run into problems every step of the way.
Trust me, been there, done that