[Chris Mangano]

I'll do my best

1. As far as I know there is no limit to levels, you could be level 1 million if you played long enough.
2. See #1
3. I don't think there is a cap on happiness drain. I think it is based on how much energy you use.
4. I would guess there will always be more districts as you gain in levels. Right now the highest district is the Midlan District available to levels 22+.