This thread is nice and active
Regarding rushing, people go for world firsts, thats why the rush like machines through the game. People like Athene, who was the world's first 80 and 85 WoW toon did the same. Its for the eFame guys. I don't agree with it, but I know a few speed-runners that drill the first playthrough, foregoing all cut-scenes / lore / health / sleep in order to accomplish the goal. They play slowly after they have attained celeb-like status.
I have closed my game to friends Quick-Joining too. My first playthrough ie: normal difficulty / up to level 30, is all by myself. I want to take my time. I even have a "mute-Mumble/TS" macro setup. Its important that I enjoy and learn D3 properly.
Regarding expansions, Diablo lore is quite deep (from my limited knowledge). They can add content at a whim. Its in the Diablo universe, not necessarily killing the guy himself. And besides, he's always getting rezzed by some or other crazy event
Regarding choosing your region, I can tell you guys how important this is.. The last thing people want to do is reroll again and again. Protip: if you can't add a friend for some reason (and the server is not lagging out), strong chance one of you is in the wrong region. The first time I launched the game, it was defaulted to AMERICAS... (i installed using the 7.6GB EU preload installer). Make sure when your friends start, you tell them.