1) You can create a custom ad form which does not have the price option, however removing the actual price tag icon would require some minor customization of the theme.
2) The theme is not specifically designed to function with the blog page as the main page. Again though, this can be achieved with some modification of the default theme files as some of our customers have done. Customizations are not officially supported, so we do not offer tutorials for this kind of change.
3) Yes, the recommended custom permalinks structure %postname% will give you the post title without the numbers e.g. yourdomain.com/ads/your-ad-title/ The way the admin demo is set up currently shows numbers which are not present on a "normal" installation.
4) AppThemes does not officially support third party plugins, so we cannot guarantee all of them will be compatible with the theme, however there are many popular plugins which do work effectively (such as All in one
SEO and others).
5) This would involve some customization of the theme on your part, but yes it is possible.
6) Vantage is not an upgrade to ClassiPress, so no it would not be a free upgrade in that instance. We do offer
AppThemes Club Packages which allow you to purchase all current and future themes for one set price, and this would generally work out as a cost effective option when purchasing multiple themes.