That is very much removed from any MMORPG type of communication.
One of the hardest parts of a client/server MMO architecture is the network layer, which uses a lossless/retry/fault-prove UDP-based protocol. Everything else sits on top. Luckily, there are tons of sample libraries by now, I suggest peeking at the leaked SW Online sony code which includes the source for their implementation.
I don't think that's true, except for the server? From the client's perspective, the current state is whatever the hell the server thinks is the sum of all previous state. So you generally don't need lossless message passing; you just need to be able to resync periodically, and trying to resend on lost messages is probably a waste of time if you can sync straight to current state
If the client/server were deterministically simulated -- thus every event must be fully represented on both sides to be in sync -- then sure, but I'm fairly positive no MMO does that