Alpha sheets can now be added to games via the edit option in the alpha sheet display. In addition, statblock embedding should also work for the [sb=show][/sb] tags. Any problems, please post in experimental features with links to the sheet and the game.
They sure do. That's part of what sets MW apart from other sites like it; we've got a great moderator community, and they're quick to put a stop to the abuses that some other boards get away with...spam, flaming, rudeness, etc.
As for houserules, this is a good place to discuss them. You can do it in the main forum of the game as Silverkiss mentions, which is also a good option, as it allows your players some input. They're more likely to follow and read the houserules if they're in on it from the ground floor. The flip side there is that thee might be more dissention--as in a playwer may not like one of your house rules and rally against it. But it's all in the name of making a game that everyone will enjoy.
Late to the party, but I thought I'd throw my two cents in, if that's alright. The basic questions first...
What others have said in this thread regarding Game Ads conduct sounds like good advice to me. Likewise, Google Draw is a fantastic tool.
As for the overarching vision for design and/or thought about the setting, I'd say that the more information I'm presented with, the more my imagination begins to work. Maybe that sounds lazy of me to say, but I know for sure that barebones homebrew worlds designed for players to add a whole lot as the game goes on sometimes make me feel like I'm creating a little pocket of reality that isn't much connected to anything the other players have done. For what it's worth, I'm a huge fan of Eberron, if you're at all considering using pre-established WotC material.
As a final thought, I'll just say that I really appreciate the care you appear to be taking towards incorporating the player's goals for their PCs into the larger structure of the game. My most rewarding experiences here at MW have been in games just like that; games in which the GM makes a concerted effort to tie the player's hopes and dreams for the PC into the plot.