In answer to your questions:
1) No, it will not work without ClassiPress, you must always have the parent theme installed first otherwise the child theme will not function. This is the nature of how child themes work, which you can read more about
here.
2) Use can use whatever currency symbol you like. When it comes to payments, PayPal which is the default payment gateway, has a list of supported currencies, and if yours does not appear in the dropdown menu, you can find
other payment gateway plugins in the AppThemes marketplace.
3) If you're not setting up the categories as locations, then it would require customization on your part if you were looking to separate listings into locations.
4) The marketplace product page for each product should clarify this, but you can also post directly to the developer in the comments section of the marketplace page to confirm.
5) There are default ad spots in the header, and single ad pages which you can configure from the ClassiPress admin dashboard. Plugins are also available to add more spaces. Thanks.