No problem, in answer to your questions:
1. Yes, there is a membership option in ClassiPress which you can see here from the
ClassiPress admin demo. You can set the duration, so whether that's 365 days that's up to you. There's no unlimited option as such though. The default payment gateway included with the theme is PayPal, however you can also purchase
other payment gateway plugins from the AppThemes marketplace if you're looking for other payment gateways.
2. Yes you can set categories specifically to only be posted in when a subscription is in place.
3. Yes, this can be done.
4. You can choose to moderate listings, but once a customer has paid for their listing it will publish automatically.
5. Yes, there are default ad banner spaces in the theme in which you can use Google Adsense code.
6. This is ultimately dependent on your hosting setup, but you can read more about this
here. Thanks.