Hi Zubin, in answer to your questions:
1) Users need to register before they can post an ad, and if you select for users not to be allowed to set their own password, they'll need to log into their email in order to retrieve it.
2) The initial theme purchase includes a lifetime license to use the theme, and 12 months of updates and support. If you choose not to renew the subscription, you can still use the theme on your site and it won't be blocked, but you won't be able to download updates or the support forums.
3) Not within the theme itself, but you can do this through customization.
4) The ad currency symbol itself can be set to whatever you like, but if you're referring to the collection of payments, if the currency is not supported by PayPal then it won't appear in the dropdown menu. You can purchase
other payment gateway plugins if you wish to find one that supports your currency. Thanks.