I could write a book on admin-to-user interactions. I have seen admins be active parts of the community and do very well, and I have seen them do very, very poorly. I've also witnessed admins detach themselves from the community and, with an active mod team, do very well, or they have seemed like they abandoned the game and users. This may sound wrong, but I would advise not getting too involved with the community. You really do not want to get too close to the user base, because it honestly does come across as unprofessional, and can lead to issues within the community later on. It is very possible to not be directly involved, but still have a good reputation as an administrator.
As for building sim hype...I think planning is a big part of it. You need to already have something to show for, something to back up your text. A wall of text is not nearly as interesting as small text interrupted by eye-catching illustration. Already have some of the "backbone" features very well thought out, if not already started programming-wise. It needs to be feasible, and sound feasible at that. If you have an idea, look for feedback on it and be willing to take criticism and consider suggestions before throwing it before the potential userbase as bait. Do not go into too much detail, but be ready to answer questions on things should they arise. You want to avoid false promises.
There are usually two things that initially catch my attention when browsing through games;
A ) The Idea; What is the core idea at the center of the game?
B ) The Art; Everyone is going to have their own preferences for art, so I cannot say much specifically on this. Just try to keep the style consistent, as mismatched styles are going to make for a bit of an eyesore and be a turn-away.
I would advise reading through the threads here posted by other game-owners and players. Even posting a general idea for a feature and asking for feedback can be really helpful-- that is if you're willing to consider the feedback.